Method and apparatus for using non-access stratum procedures in a mobile station to access resources of component carriers belonging to different radio access technologies

ABSTRACT

Methods and apparatus are disclosed for a wireless transmit/receive unit (WTRU) to perform a multi-radio access technology (RAT) access (MRA) operation. The apparatus may include a WTRU non-access stratum (NAS) entity to communicate with a first and second NAS entity of a first and second core network (CN). Alternatively, the first WTRU NAS entity communicates with a first NAS entity of a first CN, and a second WTRU NAS entity communicates with a second NAS entity of a second CN. The apparatus may include a radio resource control (RRC) entity which controls a first RAT connected to the first CN and a second RAT connected to the second CN. Alternatively, the apparatus includes an RRC entity which controls a first connection using a first RAT connected to the first CN and a second connection using a second RAT connected to a second CN.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/525,432 filed Aug. 19, 2011, the contents of which are herebyincorporated by reference herein.

BACKGROUND

The demand for improved network coverage, improved capacity andincreasing bandwidth for both voice and data services in wirelesssystems has led to continuous development of a number of radio accesstechnologies (RATs) including, for example, wideband channel divisionmultiple access (WCDMA) and long term evolution (LTE). WCDMA may supportthe simultaneous use of two high speed downlink packet access (HSDPA)downlink component carriers (2C-HSDPA). LTE may support simultaneoustransmission and/or reception using the radio resources of a pluralityof component carriers between a network node, for example between anevolved Node-B (eNodeB), and a wireless transmit/receive unit (WTRU)within the same transmission interval.

Some operators may deploy both WCDMA/high speed packet access (HSPA) andLTE in the same coverage areas, with LTE as a data enhancement overlay.LTE deployments may have a coverage that is similar to existingWCDMA/HSPA deployments, and multi-mode WTRUs, (e.g., supporting bothWCDMA/HSPA and LTE accesses), may be widely deployed.

Spectrum is a costly resource and not all frequency bands may beavailable to all operators, although it may be expected that manyoperators may offer support for both HSPA and LTE services. Carrieraggregation scenarios may typically be limited to at most 2-3 componentcarriers per RAT for a given operator. In addition, legacy deploymentsmay be maintained for a foreseeable future while LTE is being deployed,which may lead to a situation where operators may see periods ofunderutilization of radio resources, spectrum and capacity in one oftheir RATs.

Therefore, there is a need in the art for a WTRU to operatesimultaneously on multiple frequencies, where the WTRU operates on atleast one of the frequencies according to a different RAT.

SUMMARY

Described herein are methods related to how a WTRU may concurrentlyoperate on a plurality of radio access technologies (RAT), using radioresources of at least one cell on which the WTRU operates according to afirst RAT and radio resources of at least one cell on which the WTRUoperates according to a second RAT. Methods described herein may beapplicable, without limitation, to this type of operation. The methodsdescribed herein may also possibly be applied in any combinationthereof, including any combinations of the embodiments provided asexample.

A wireless transmit/receive unit (WTRU) to perform a multi-radio accesstechnology (RAT) access (MRA) operation is disclosed. The WTRU mayinclude a WTRU non-access stratum (NAS) entity configured to communicatewith a first NAS entity of a first core network and a second NAS entityof a second core network; and a radio resource control (RRC) entityconfigured to control a first connection using a first RAT and a secondconnection using a second RAT, wherein the first RAT is connected to thefirst core network and the second RAT is connected to the second corenetwork.

A wireless transmit/receive unit (WTRU) to perform a multi-radio accesstechnology (RAT) access (MRA) operation is disclosed. The WTRU mayinclude a WTRU non-access stratum (NAS) entity configured to communicatewith a first NAS entity of a first core network and a second NAS entityof a second core network; a first radio resource control (RRC) entityconfigured to control a first connection using a first RAT; and a secondRRC entity configured to control a second connection using a second RAT,wherein the first RAT is connected to the first core network and thesecond RAT is connected to the second core network.

A wireless transmit/receive unit (WTRU) to perform a multi-radio accesstechnology (RAT) access (MRA) operation is disclosed. The WTRU mayinclude a first WTRU non-access stratum (NAS) entity configured tocommunicate with a first NAS entity of a first core network; a secondWTRU NAS entity configured to communicate with a second NAS entity of asecond core network; and a radio resource control (RRC) entityconfigured to control a first connection using a first RAT and a secondconnection using a second RAT, wherein the first RAT is connected to thefirst core network and the second RAT is connected to the second corenetwork.

A wireless transmit/receive unit (WTRU) to perform a multi-radio accesstechnology (RAT) access (MRA) operation is disclosed. The WTRU mayinclude a first WTRU non-access stratum (NAS) entity configured tocommunicate with a first NAS entity of a first core network; a secondWTRU NAS entity configured to communicate with a second NAS entity of asecond core network; and a radio resource control (RRC) entityconfigured to control a first connection using a first RAT; and a secondRRC entity configured to control a second connection using a second RAT,wherein the first RAT is connected to the first core network and thesecond RAT is connected to the second core network.

A method of a wireless transmit/receive unit (WTRU) performing amulti-radio access technology (RAT) access (MRA) operation is disclosed.The method may include determining a first cell of a first RAT thatsupports MRA operation; attaching to a first NAS entity of a first corenetwork via the first cell using a WTRU non-access stratum (NAS) entityconfigured to communicate with the first NAS entity of the first corenetwork and a second NAS entity of a second core network, and using aradio resource control (RRC) entity configured to control a firstconnection using the first RAT and a second connection using a secondRAT, wherein the first RAT is connected to the first core network andthe second RAT is connected to the second core network; determining asecond cell of the second RAT that supports MRA operation; and attachingto the second NAS entity using the WRTU NAS entity and the RRC entity.

A method of a wireless transmit/receive unit (WTRU) performing amulti-radio access technology (RAT) access (MRA) operation is disclosed.The method may include determining a first cell of a first RAT thatsupports MRA operation; attaching to a first NAS entity of a first corenetwork via the first cell using a WTRU non-access stratum (NAS) entityconfigured to communicate with the first NAS entity of the first corenetwork and a second NAS entity of a second core network, and using afirst radio resource control (RRC) entity configured to control a firstconnection using the first RAT, wherein the first RAT is connected tothe first core network; determining a second cell of a second RAT thatsupports MRA operation; and attaching to the second NAS entity via thesecond cell using the WRTU NAS entity and a second RRC entity configuredto control a second connection using the second RAT, wherein the secondRAT is connected to the second core network.

A method of a wireless transmit/receive unit (WTRU) performing amulti-radio access technology (RAT) access (MRA) operation is disclosed.The method may include determining a first cell of a first RAT thatsupports MRA operation; attaching to a first NAS entity of a first corenetwork via the first cell using a first WTRU non-access stratum (NAS)entity configured to communicate with a first NAS entity of a first corenetwork, and using a radio resource control (RRC) entity configured tocontrol a first connection using the first RAT and a second connectionusing a second RAT, wherein the first RAT is connected to the first corenetwork and the second RAT is connected to the second core network;determining a second cell of the second RAT that supports MRA operation;and attaching to the second NAS entity via the second cell using asecond WTRU NAS entity configured to communicate with the second NASentity of the second core network and the RRC entity.

A method of a wireless transmit/receive unit (WTRU) performing amulti-radio access technology (RAT) access (MRA) operation is disclosed.The method may include determining a first cell of a first RAT thatsupports MRA operation; attaching to a first NAS entity via the firstcell using a first WTRU non-access stratum (NAS) entity configured tocommunicate with a first NAS entity of a first core network, and using afirst radio resource control (RRC) entity configured to control a firstconnection using the first RAT, wherein the first RAT is connected tothe first core network; determining a second cell of a second RAT thatsupports MRA operation; and attaching to a second NAS entity via thesecond cell using a second WRTU NAS entity and a second RRC entityconfigured to control a second connection using the second RAT, whereinthe second RAT is connected to the second core network.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A shows an example communications system in which one or moredisclosed embodiments may be implemented;

FIG. 1B shows an example WTRU that may be used within the communicationssystem 100 shown in FIG. 1A;

FIG. 1C is a system diagram of the RAN and the core network 106according to an embodiment;

FIG. 1D shows another example RAN and another example CN 106 that may beused within the communications system shown in FIG. 1A;

FIG. 2A shows a WRTU communicating with two different RANs 204 a and 204b with two core networks 206 a and 206 b configured to communicate withone another;

FIG. 2B shows a WRTU communicating with two different base stations withtwo RANs configured to communicate with one another;

FIGS. 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H, and 3I schematically illustratesdifferent network architectures to facilitate MRA operation according toexamples of WTRUs;

FIG. 4 schematically illustrates radio protocols, a non-access stratus(NAS) protocols, and an access stratus (AS) protocols;

FIGS. 5A, 5B, 5C, and 5D schematically illustrate different examples ofMRA WTRUs with different numbers of NAS entities and different numbersof RRC entities;

FIG. 6 schematically illustrates an MRA WTRU for determining which cellto access for MRA operation;

FIG. 7 schematically illustrates the WTRU receiving a message from thenetwork to initiate MRA operation;

FIG. 8 is a flow diagram of an example combined attach procedure from aneUTRA (LTE/EPS) RAT;

FIG. 9 is schematic illustration of a flow diagram of another example ofa combined attach method from an eUTRA (LTE/EPS) RAT where a PDP contextis created for the WTRU in the GPRS/UMTS domain and in the EPS domain;

FIG. 10 is a schematic illustration of a flow diagram of an example of acombined attach procedure from a UTRA (GPRS/UMTS/HSPA) RAT where a PDPcontext is activated in the EPS domain but no in the GPRS/UMTS domain;

FIG. 11 is a schematic illustration of a flow diagram of another exampleof a combined attach procedure from a UTRA (GPRS/UMTS/HSPA) RAT where aPDP context is activated in the GPRS/UMTS/HSPA domain in addition to thePDP context activated in the EPS domain;

FIG. 12 is a schematic illustration of a flow diagram of an exampleRAT-specific attach procedure for a sequential operation;

FIG. 13 is a schematic illustration of a flow diagram of an exampleRAT-specific concurrent attach method;

FIG. 14 is a schematic illustration of a flow diagram of an exampleWTRU-initiated combined detach method from an eUTRA (LTE/EPS) RAT;

FIG. 15 is schematic illustration of a flow diagram of an example WTRUinitiated combined detach method a UTRA (GPRS/UMTS/HSPA) RAT;

FIG. 16 is a schematic illustration of a flow diagram of an examplemobility management entity (MME)-initiated combined detach method;

FIG. 17 is a schematic illustration of a flow diagram of an exampleserving general packet radio service (GPRS) support node(SGSN)-initiated combined detach method;

FIG. 18 is a flow diagram of an example home location register(HLR)-initiated combined detach method;

FIG. 19 is schematic illustration of a flow diagram of an example of acombined attach request method from either a UTRA (GPRS/UMTS/HSPA) RATor an EUTRA (EPS/LTE) RAT leading to an attachment of the WTRU to both a3GPP network and a non-3GPP network;

FIG. 20 is schematic illustration of a flow diagram of an example of acombined attach request method from a non-3GPP RAT leading to anattachment of the WTRU to both 3GPP and non-3GPP network;

FIG. 21 is a schematic illustration of a flow diagram of another exampleof a combined attach method leading to an attachment of the WTRU to botha 3GPP network and a non-3GPP network;

FIGS. 22A and 22B schematically illustrate different methods forperforming session management;

FIG. 23 schematically illustrates an example of a table that illustratesan EPS attach type information elements (IE) for Combined ATTACHProcedure with the introduction of two new Information Element (IE);

FIG. 24 illustrates an example of a table that illustrates an EPS attachtype information elements (IE) for Combined DETACH Procedure;

FIG. 25 schematically illustrates an example of a table that illustratesa GPRS/UMTS Attach Status Information Element (IE) as introduced in themodified EPS attach accept message illustrated in FIG. 24;

FIG. 26 schematically illustrates an example of a table that illustratesanother example of a modified EPS attach accept message content;

FIG. 27 schematically illustrates an example of a GPRS/UMTS PDP contextmessage content as an example of the modified EPS attach accept messageillustrated in FIG. 26;

FIG. 28 schematically illustrates an example table of GPRS/UMTS attachaccept message content;

FIG. 29 schematically illustrates an example of a modified table ofinformation elements (IE) for a detach type IE used in an EPS detachrequest message for a combined detach procedure;

FIG. 30 schematically illustrates an example of a table of GPRS/UMTSattach type IEs used in a GPRS/UMTS attach request message for acombined attach;

FIG. 31 schematically illustrates an example of a modified table ofGPRS/UMTS attach accept message content for a combined attach procedure;

FIG. 32 schematically illustrates an example table for EPS attach acceptmessage content;

FIG. 33 schematically illustrates an example of a modified table ofGPRS/UMTS attach accept message content for a combined attach procedure;

FIG. 34 schematically illustrates an example table for GPTS/UMTSactivate PDP context accept message content;

FIG. 35 schematically illustrates another example table for EPS attachedaccept message; and

FIG. 36 schematically illustrates an example of a table for a GPRS/UMTSdetach type of information element for a combined detach.

DETAILED DESCRIPTION

FIG. 1A shows an example communications system 100 in which one or moredisclosed embodiments may be implemented. The communications system 100may be a multiple access system that provides content, such as voice,data, video, messaging, broadcast, and the like, to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include WTRUs 102a, 102 b, 102 c, 102 d, a radio access network (RAN) 104, a core network(CN) 106, a public switched telephone network (PSTN) 108, the Internet110, and other networks 112, though it will be appreciated that thedisclosed embodiments contemplate any number of WTRUs, base stations,networks, and/or network elements. Each of the WTRUs 102 a, 102 b, 102c, 102 d may be any type of device configured to operate and/orcommunicate in a wireless environment. By way of example, the WTRUs 102a, 102 b, 102 c, 102 d may be configured to transmit and/or receivewireless signals and may include user equipment (UE), a mobile station,a fixed or mobile subscriber unit, a pager, a cellular telephone, apersonal digital assistant (PDA), a smartphone, a laptop, a notebook, apersonal computer, a wireless sensor, consumer electronics, and thelike.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the CN 106, the Internet 110, and/or theother networks 112. By way of example, the base stations 114 a, 114 bmay be a base transceiver station (BTS), a Node-B, an evolved Node-B(eNB), a Home Node-B (HNB), a Home eNB (HeNB), a site controller, anaccess point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, and the like. The base station 114 a and/or the base station 114b may be configured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple-output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link, (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, and thelike). The air interface 116 may be established using any suitable radioaccess technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as universal mobiletelecommunications system (UMTS) terrestrial radio access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as high-speed packet access(HSPA) and/or evolved HSPA (HSPA+). HSPA may include high-speed downlink(DL) packet access (HSDPA) and/or high-speed uplink (UL) packet access(HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as evolved UTRA (E-UTRA),which may establish the air interface 116 using long term evolution(LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,worldwide interoperability for microwave access (WiMAX)), CDMA2000,CDMA2000 1X, CDMA2000 evolution-data optimized (EV-DO), Interim Standard2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856(IS-856), global system for mobile communications (GSM), enhanced datarates for GSM evolution (EDGE), GSM/EDGE RAN (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, HNB, HeNB,or AP, for example, and may utilize any suitable RAT for facilitatingwireless connectivity in a localized area, such as a place of business,a home, a vehicle, a campus, and the like. In one embodiment, the basestation 114 b and the WTRUs 102 c, 102 d may implement a radiotechnology such as IEEE 802.11 to establish a wireless local areanetwork (WLAN). In another embodiment, the base station 114 b and theWTRUs 102 c, 102 d may implement a radio technology such as IEEE 802.15to establish a wireless personal area network (WPAN). In yet anotherembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayutilize a cellular-based RAT, (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A,and the like), to establish a picocell or femtocell. As shown in FIG.1A, the base station 114 b may have a direct connection to the Internet110. Thus, the base station 114 b may not be required to access theInternet 110 via the CN 106.

The RAN 104 may be in communication with the CN 106, which may be anytype of network configured to provide voice, data, applications, and/orvoice over Internet protocol (VoIP) services to one or more of the WTRUs102 a, 102 b, 102 c, 102 d. For example, the CN 106 may provide callcontrol, billing services, mobile location-based services, pre-paidcalling, Internet connectivity, video distribution, and the like, and/orperform high-level security functions, such as user authentication.Although not shown in FIG. 1A, it will be appreciated that the RAN 104and/or the CN 106 may be in direct or indirect communication with otherRANs that employ the same RAT as the RAN 104 or a different RAT. Forexample, in addition to being connected to the RAN 104, which may beutilizing an E-UTRA radio technology, the CN 106 may also be incommunication with another RAN (not shown) employing a GSM radiotechnology.

The CN 106 may also serve as a gateway for the WTRUs 102 a, 102 b, 102c, 102 d to access the PSTN 108, the Internet 110, and/or other networks112. The PSTN 108 may include circuit-switched telephone networks thatprovide plain old telephone service (POTS). The Internet 110 may includea global system of interconnected computer networks and devices that usecommon communication protocols, such as the transmission controlprotocol (TCP), user datagram protocol (UDP) and the Internet protocol(IP) in the TCP/IP suite. The networks 112 may include wired or wirelesscommunications networks owned and/or operated by other serviceproviders. For example, the networks 112 may include another CNconnected to one or more RANs, which may employ the same RAT as the RAN104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B shows an example WTRU 102 that may be used within thecommunications system 100 shown in FIG. 1A. As shown in FIG. 1B, theWTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element, (e.g., an antenna), 122, a speaker/microphone124, a keypad 126, a display/touchpad 128, a non-removable memory 130, aremovable memory 132, a power source 134, a global positioning system(GPS) chipset 136, and peripherals 138. It will be appreciated that theWTRU 102 may include a sub-combination of the foregoing elements whileremaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), amicroprocessor, one or more microprocessors in association with a DSPcore, a controller, a microcontroller, an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA)circuit, an integrated circuit (IC), a state machine, and the like. Theprocessor 118 may perform signal coding, data processing, power control,input/output processing, and/or any other functionality that enables theWTRU 102 to operate in a wireless environment. The processor 118 may becoupled to the transceiver 120, which may be coupled to thetransmit/receive element 122. While FIG. 1B depicts the processor 118and the transceiver 120 as separate components, the processor 118 andthe transceiver 120 may be integrated together in an electronic packageor chip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals.

In another embodiment, the transmit/receive element 122 may be anemitter/detector configured to transmit and/or receive IR, UV, orvisible light signals, for example. In yet another embodiment, thetransmit/receive element 122 may be configured to transmit and receiveboth RF and light signals. The transmit/receive element 122 may beconfigured to transmit and/or receive any combination of wirelesssignals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. For example, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122, (e.g., multiple antennas), fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, orLTE and WCDMA/HSPA, as examples.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),and the like), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station, (e.g., base stations 114 a, 114 b), and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. The WTRU 102 may acquire location informationby way of any suitable location-determination method while remainingconsistent with an embodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ aUTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102 cover the air interface 116. The RAN 104 may also be in communicationwith the core network 106. As shown in FIG. 1C, the RAN 104 may includeNode-Bs 140 a, 140 b, 140 c, which may each include one or moretransceivers for communicating with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The Node-Bs 140 a, 140 b, 140 c may each beassociated with a particular cell (not shown) within the RAN 104. TheRAN 104 may also include RNCs 142 a, 142 b. It will be appreciated thatthe RAN 104 may include any number of Node-Bs and RNCs while remainingconsistent with an embodiment.

As shown in FIG. 1C, the Node-Bs 140 a, 140 b may be in communicationwith the RNC 142 a. Additionally, the Node-B 140 c may be incommunication with the RNC 142 b. The Node-Bs 140 a, 140 b, 140 c maycommunicate with the respective RNCs 142 a, 142 b via an Iub interface.The RNCs 142 a, 142 b may be in communication with one another via anIur interface. Each of the RNCs 142 a, 142 b may be configured tocontrol the respective Node-Bs 140 a, 140 b, 140 c to which it isconnected. In addition, each of the RNCs 142 a, 142 b may be configuredto carry out or support other functionality, such as outer loop powercontrol, load control, admission control, packet scheduling, handovercontrol, macrodiversity, security functions, data encryption, and thelike.

The core network 106 shown in FIG. 1C may include a media gateway (MGW)144, a mobile switching center (MSC) 146, a serving GPRS support node(SGSN) 148, and/or a gateway GPRS support node (GGSN) 149. While each ofthe foregoing elements are depicted as part of the core network 106, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 142 a in the RAN 104 may be connected to the MSC 146 in the corenetwork 106 via an IuCS interface. The MSC 146 may be connected to theMGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices.

The RNC 142 a in the RAN 104 may also be connected to the SGSN 148 inthe core network 106 via an IuPS interface. The SGSN 148 may beconnected to the GGSN 149. The SGSN 148 and the GGSN 149 may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between and the WTRUs102 a, 102 b, 102 c and IP-enabled devices.

As noted above, the core network 106 may also be connected to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

The CN 106 may include a home network subscriber node, which performsauthentication, security context preservation and security keygeneration for WTRUs. The home network subscribers node may be referredto as a home location register (HLR) or home subscriber server (HSS).

FIG. 1D shows another example RAN 104 and another example CN 106 thatmay be used within the communications system 100 shown in FIG. 1A. Asnoted above, the RAN 104 may employ an E-UTRA radio technology tocommunicate with the WTRUs 102 a, 102 b, 102 c over the air interface116. The RAN 104 may also be in communication with the CN 106.

The RAN 104 may include eNode-B's (eNBs) 150 a, 150 b, 150 c, though itwill be appreciated that the RAN 104 may include any number of eNBswhile remaining consistent with an embodiment. The eNBs 150 a, 150 b,150 c may each include one or more transceivers for communicating withthe WTRUs 102 a, 102 b, 102 c over the air interface 116. In oneembodiment, the eNBs 150 a, 150 b, 150 c may implement MIMO technology.Thus, the eNB 150 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNBs 150 a, 150 b, 150 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, and the like. As shown in FIG. 1D, the eNBs 150 a, 150 b, 150c may communicate with one another over an X2 interface.

The CN 106 shown in FIG. 1D may include a mobility management entity(MME) 152, a serving gateway 154, and a packet data network (PDN)gateway (GW) 156. While each of the foregoing elements is depicted aspart of the CN 106, it will be appreciated that any one of theseelements may be owned and/or operated by an entity other than the CNoperator.

The MME 152 may be connected to each of the eNBs 150 a, 150 b, 150 c inthe RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 152 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 152 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 154 may be connected to each of the eNBs 150 a, 150b, 150 c in the RAN 104 via the S1 interface. The serving gateway 154may generally route and forward user data packets to/from the WTRUs 102a, 102 b, 102 c. The serving gateway 154 may also perform otherfunctions, such as anchoring user planes during inter-eNB handovers,triggering paging when DL data is available for the WTRUs 102 a, 102 b,102 c, managing and storing contexts of the WTRUs 102 a, 102 b, 102 c,and the like.

The serving gateway 154 may also be connected to the PDN gateway 156,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway, (e.g., an IP multimediasubsystem (IMS) server), that serves as an interface between the CN 106and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102 a,102 b, 102 c with access to other networks 112, which may include otherwired or wireless networks that are owned and/or operated by otherservice providers.

The CN 106 may include a home network subscriber node, which performsauthentication, security context preservation and security keygeneration for WTRUs. The home network subscribers node may be referredto as a home location register (HLR) or home subscriber server (HSS).

FIG. 1C described a UMTS/GPRS system. FIG. 1D described a LTE system.The system could be another type of system such as GERAN or WMAX.

In examples, LTE may include EPS and EPS may include LTE.

FIG. 2A shows a WRTU communicating with two different RANs 204 a and 204b with two core networks 206 a and 206 b configured to communicate withone another. Illustrated in FIG. 2A is a WRTU 102, two RANs 204 a, 204b, two base stations 214 a, 214 b, and two core networks 206 a, 206 b.As illustrated in FIG. 1A, the core networks 206A and 206B may beconfigured to communicate with a PSTN 108, the Internet 110, and othernetworks 112.

The WRTU 102 may be a multi-mode WTRU 102. A multi-mode WTRU 102 is anymobile terminal supporting at least two different radio accesstechnologies (RAT). For example, multi-mode WRTU 102 supports two ormore of: GSM, WCDMA, HSPA, HSDPA, HSUPA and LTE, IEEE 802.11b/a/g/n,IEEE 802.16a/e and 802.20, as well as CDMA2000 1x and CDMA2000 EV-DO. Asillustrated, the WTRU 102 may be communicating with two different basestations 214 a and 214 b, which may be part of two RANs 204 a and 204 b,respectively. The RAN 204 a and core network 206 a may be an EPScommunication system and RAN 204 b and core network 206 b may be aUTMS/GPRS communication system. The two core networks 206 a and 206 bmay communicate 220 with one another to assist in coordinating thecommunication between the WRTU 102 and the two core networks 206 a, 206b, and between the WTRU 102 and the two base stations 214 a and 214 b.The communication 220 may include different entities communicating withone another within the core network 206 a, 206 b. For example, a MMEentity in core network 206 a may communicate with a SGSN entity in corenetwork 206 b. The two base stations 214 a, 214 b and two RANs 204 a,204 b may be as described in conjunction with for FIG. 1.

FIG. 2B shows a WRTU communicating with two different base stations withtwo RANs configured to communicate with one another. Illustrated in FIG.2A is a WRTU 102, two RANs 204 c, 204 d, two base stations 214 c, 214 d,and two core networks 206 c, 206 d. As illustrated in FIG. 1A, the corenetworks 206 c and 206 d may be configured to communicate with PSTN 108,the Internet 110, and other networks 112.

The WRTU 102 may be a multi-mode WTRU. As illustrated, the WTRU 102 maybe communicating with two different base stations 214 c and 214 d, whichmay be part of two RANs 204 c and 204 d, respectively. The RAN 204 c andcore network 106 c may be an EPS communication system and RAN 204 d andcore network 106 d may be a UMTS/GPRS communication system. The two RANs204 c and 204 d may communicate 222 with one another to assist incoordinating the communication between the WRTU 102 and the two basestations 214 a and 214 b. The communication 220 may include differententities communicating with one another within the RANs 204 c, 204 d.The two base stations 214 c, 214 d and two core networks 206 c, 206 dmay be as described for FIG. 1.

A cell (not shown) that is served by a base station 214 a, 214 b, 214 c,and 214 d may be a primary cell (PCell), or a secondary cell (SCell),and when a cell is either a PCell or a SCell the cell may be considereda serving cell. PCell, SCell, and serving cell are discussed furtherbelow.

A component carrier (CC) may include a frequency on which the WTRU 102operates the air interface 216. The air interface 216 may comprise oneor more physical channels. For example, a WTRU 102 may receivetransmissions on a down-link (DL) CC that may comprise a plurality of DLphysical channels that comprise the air interface 216. As anotherexample, a WTRU 102 may perform transmissions on a UL CC that maycomprise of a plurality of UL physical channels that comprise the airinterface 216.

For example, for LTE, the DL physical channels include the physicalcontrol format indicator channel (PCFICH), the physical HARQ indicatorchannel (PHICH), the physical data control channel (PDCCH), the physicalmulticast data channel (PMCH) and the physical data shared channel(PDSCH). On the PCFICH, the WTRU 102 may receive control data indicatingthe size of the control region of the DL CC. On the PHICH, the WTRU 102may receive control data indicating HARQ positive acknowledgement(ACK)/negative acknowledgement (NACK) feedback for a previous uplinktransmission. On the PDCCH, the WTRU 102 may receive DL controlinformation (DCIs) messages used for the purpose of scheduling of DL andUL resources. On the PDSCH, the WTRU 102 may receive user and/or controldata. For example, a WTRU 102 may transmit on a UL CC.

For LTE, the UL physical channels include the physical UL controlchannel (PUCCH) and the physical UL shared channel (PUSCH). On thePUSCH, the WTRU 102 may transmit user and/or control data. On the PUCCH,and in some case on the PUSCH, the WTRU 102 may transmit UL controlinformation. For example, the WTRU 102 may transmit channel qualityindicator (CQI)/precoding matrix indicator (PMI)/rank indicator (RI) orscheduling request (SR) and/or HARQ ACK/NACK feedback. On a UL CC, theWTRU 102 may also be allocated dedicated resources for transmission ofsounding and reference signals (SRS).

For example, for HSDPA, a shared channel may be used for downlinktransmission: the high-speed downlink shared channel (HS-DSCH). TheHS-DSCH may be a transport channel on which the WTRU 102 receives userdata and/or control signaling from logical channels, such as a dedicatedtransport channel (DTCH), a dedicated control channel (hereafter DCCH),a common control channel (CCCH), or possibly also a broadcast controlchannel (BCCH). The WTRU 102 may receive the HS-DSCH on the high-speedDL shared channel (HS-PDSCH). The WTRU 102 may receive DL controlsignaling for scheduling of the HS-PDSCH, (e.g., transport formatincluding channelization code, modulation scheme and transport blocksize), as well as other types of control signaling for, e.g.,discontinuous reception (DRX)/discontinuous transmission (DTX)activation/deactivation, and/or activation/deactivation commands foradditional HSPA cells on the high-speed shared control channel(HS-SCCH). The WTRU 102 may transmits UL feedback control informationrelated to HS-PDSCH transmissions and/or related to HS-SCCH orders,which feedback consists of HARQ feedback, CQI, as well as pre-codingcontrol information (PCI) if the WTRU 102 is configured for MIMOoperation, on the high-speed dedicated physical control channel(HS-DPCCH), one for each configured HS-DSCH. Power control commands maybe received by the WTRU 102 on the DPCH or on the fractional DPCH(F-DPCH). There is no soft-handover for HS-SCCH and HS-DPSCH.

For example, for HSUPA, fast scheduling and fast HARQ for soft combiningmay be supported, and the enhanced dedicated channel (E-DCH) may beused. Soft handover may be supported for HSUPA. The E-DCH may be mappedon the dedicated physical data channel (E-DPDCH). There may be zero, oneor more E-DPDCH(s) on each radio link. The WTRU 102 may transmit controlinformation associated with the E-DCH on the E-DCH dedicated physicalcontrol channel (E-DPCCH). There may be one E-DPCCH on each radio link.The dedicated physical downlink channels needed for UL transmissions maybe the F-DPCH, the E-DCH relative grant channel (E-RGCH), the E-DCHabsolute grant channel (E-AGCH) and the E-DCH HARQ indicator channel(E-HICH). The WTRU 102 may receive power control commands on the DPCH oron the fractional DPCH. The WTRU 102 may receive UL relative grants fromthe serving and non serving radio links, over the associated E-RGCHconfigured by higher layer signaling for each serving and non-servingradio link. The WTRU 102 may receive absolute grants for E-DCH from theserving E-DCH cell on the E-AGCH configured by higher layer signaling.The WTRU may receive HARQ ACK/NACK feedback on the E-HICH.

A cell may transmit information via a DL CC which may be linked to a ULCC based on system information (SI) received by the WTRU 102, eitherbroadcasted on the DL CC or possibly using dedicated configurationsignaling from the core network 206. For example, when broadcasted onthe DL CC, the WTRU 102 may receive the uplink frequency and bandwidthof the linked UL CC as part of the system information element, (e.g.,when in RRC_IDLE for LTE, or when in idle/CELL_FACH for WCDMA, i.e.,when the WTRU 102 does not yet have a radio resource connection to thenetwork).

A primary cell (PCell) may include, the cell operating on the primaryfrequency in which the WTRU 102 may perform the initial access to thecommunication system, e.g., in which it may either perform the initialconnection establishment procedure, or initiate the connectionre-establishment procedure, or the cell indicated as the PCell in ahandover procedure. A cell may be considered a PCell as a result of afrequency being indicated as part of the radio resource connection (RRC)configuration procedure. Some functions may be only supported on thePCell. For example, the UL CC of the PCell may correspond to the CCwhose physical uplink control channel resources are configured to carryall HARQ ACK/NACK feedback for a given WTRU 102.

For example, in LTE the WTRU 102 may use the PCell to derive theparameters for the security functions and for upper layer systeminformation such as none access system (NAS) mobility information. Otherfunctions that may be supported only on the PCell DL include systeminformation (SI) acquisition and change monitoring procedures on thebroadcast channel (BCCH), and paging. Additionally, in WCDMA the PCellmay be similar to the PCell described above for LTE.

A secondary cell (SCell) may include the cell operating on a secondaryfrequency which may be configured once a radio resource controlconnection (RRC) is established and which may be used to provideadditional radio resources. System information relevant for operation inthe concerned SCell is typically provided using dedicated signaling whenthe SCell is added to the configuration of the WTRU 102. Although theparameters may have different values than those broadcasted on thedownlink of the SCell using the system information (SI) signaling, thisinformation is herein referred to as SI of the concerned SCellindependently of the method used by the WTRU 102 to acquire thisinformation.

PCell DL and PCell UL correspond to the DL CC and the UL CC of thePCell, respectively. SCell DL and SCell UL correspond to the DL CC andthe UL CC of a SCell, respectively. A serving cell may be either a PCellor a SCell.

A WTRU 102 may be configured with one or more of a PCell DL, a PCell UL,a SCell DL and a SCell UL.

A WTRU 102 that uses multi-RAT access (MRA) may include any multi-modeWTRU 102 configured for operation with at least one CC with a first RATfor DL CC and UL CC, and with at least one CC of a second RAT for atleast one of a DL CC or a UL CC. In addition, the WTRU 102 may operateon the different component carriers either simultaneously, ornear-simultaneously in time. In embodiments, an MRA WTRU 102 may operatewith two or more RATs sequentially operating on the same frequency band.

In examples, UTRAN/GERAN, UMTS/HSPA, UTRAN, UMTS, HSPA, andGPRS/UMTS/HSPA may be used interchangeably. In examples, LTE, EPS andEUTRAN may be used interchangeably.

FIGS. 3A, 3B, 3C, 3D, 3E, 3F, 3G, 3H, and 3I schematically illustratesdifferent network architectures to facilitate MRA operation according toexamples of WTRUs. FIG. 3A schematically illustrates an existingarchitecture 310.

FIG. 3B schematically illustrates an example of a network architecture320 that facilitates MRA operation according to examples of WTRUsdisclosed herein. Illustrated in FIG. 3B is the architecture 310 withthree new interfaces S5/Gn 322, 324 Iur/Iub/X2, and S1-MME/Iu-CP 326.S5/Gn 322 may be a new direct interface between PGW and RNC. S5/Gn 322may be similar to the S5 interface, the S12 interface, or the Gninterface, or any combination of those interfaces to facilitate MRAoperation of the WTRUs disclosed herein. S1-MME/Iu-CP 326 may be adirect interface between SGSN and the eNB. S1-MME/Iu-CP 326 may besimilar to the S1-MME interface, the S1-U, the Iu-CP interface, or theIu-UP, or any combination of those interfaces to facilitate MRAoperation of the WTRUs disclosed herein. Iur/Iub/X2 324 may be aninterface between RNC and eNB. Iur/Iub/X2 324 may be similar to the Iurinterface, the Iub interface, or the X2 interface, or any combination ofthose interfaces to facilitate MRA operation of the WTRUs disclosedherein. For example, for the example WTRU with one NAS entity and twoRRC entities, the PS traffic split may be done at the SGSN (or at theGGSN) where the SGSN (or GGSN) determines whether to route the datapackets addressed to the WTRU through the RNC or through the eNB orthrough both the RNC and the eNB. As another example, for a WTRU withone NAS entity and two RRC entities, the traffic split may be done atthe PGW (or at the SGW) where the PGW (or the SGW) determines to eitherroute the data packets though the eNB, through the RNC, or through bothRNC and eNB.

FIGS. 3C, 3D and 3E are different examples of FIG. 3B according toexamples.

FIG. 3F is another network architecture option where there is a newdirect interface between the SGW and the NodeB and a new directinterface between eNB and NodeB. For example in the scenario of a WTRUwith one single NAS controlling entity and two RRC controlling entities,the traffic addressed to the UE may be split at the SGW where the SGWmakes the decision to either route the data packets through the eNB orthrough the NodeB or through both eNB and Node B. In addition, the eNBmay decide to route some or all of the data packets addressed to the UEvia the Node B instead of a direct transmission to the UE over the Uuinterface. Similarly, the NodeB may determine to route some or all ofthe data packets addressed to the UE via the eNB instead of a directtransmission to the UE over the Uu interface.

FIGS. 3G, 3H, and 3I illustrates a traffic split at the RNC toward NodeBand eNodeB or traffic aggregation from eNodeB and NodeB at the RNC forexample in the scenario of a WTRU with one single NAS controlling entityand two RRC controlling entities with different core networkconfigurations. In FIGS. 3G, 3H, and 3I the lines may indicate one ormore of control paths or user data paths as well as other protocols.

FIG. 4 schematically illustrates a WTRU 102, RAN 104, and a CN 106,communication interface 414, communication interface 416, non-accessstratum (NAS) protocol communication 434, radio protocol communication418, and S1 protocol communication 422. The protocols used tocommunicate among the WTRU 102, RAN 104, and the CN 106 are classifiedinto two types: access stratum (AS) protocols 404, which include radioprotocols 408 and S1 protocols 412, and the NAS protocols 420. and radioprotocols, a non-access stratus (NAS) protocols, and an access stratus(AS) protocols. The WTRU 102 communicates over the radio protocolcommunication 418 with the RAN 104 using radio protocols 408, whichinclude RRC, PDCP, PHY, RLC, and MAC. The RAN 104 communicates with theCN 106 over the S1 protocol communication 422 using the S1 protocol,which may include luh, lu, and S1.

The WTRU 102 and RAN 104 communicates with one another over the NASprotocol communication 434 using NAS protocols 420, which may includeCM, MM, GMM, SM, EMM, and ESM. Communication indicator 432 indicatesthat the actual messages between the WTRU 102 and the CN 106 for the NASprotocols actually pass through the access stratum 404 for delivery.

The NAS 420 layer supports signaling and traffic between the CN 106 andthe WTRU 102 or between the WTRU 102 and the CN 106. The NAS protocolmay include the following: connection management (CM), mobilitymanagement (MM), general packet radio service (GPRS) mobility management(GMM), session management (SM), evolved packet system (EPS) mobilitymanagement (EMM), and EPS system session management (ESM), subscriptionmanagement, security management and charging.

FIGS. 5A, 5B, 5C, and 5D schematically illustrate different examples ofMRA WTRUs with different numbers of NAS entities and different numbersof RRC entities. FIG. 5A schematically illustrates an MRA WTRU 502 a, aNAS entity 534 a, an RRC 508 a entity, air interfaces 516, 517, RANs504, 505, core networks 506, 507, and PDN Network 509. The MRA WTRU 502a may be attached to the two core networks 506, 507, via the two RANs504, 505, and the MRA WTRU 502 a may be connected to PDN 509 via one orboth of the core networks 506, 507. The core networks 506, 507 each havea NAS entity 512 a, 513 a, respectively. The NAS entities 512 a, 513 amay comprise more than one entity that resides in the various networkcomponents that comprise the core networks 506, 507.

A single NAS entity 534 a controls the NAS layer protocols 402 betweenthe MRA WTRU 502 a and the NAS 512 entity of the core network 506 andthe NAS entity 513 of the core network 507. The MRA WTRU 502 a may beconnected to PDN 509. The data traffic from the connection to the PDN509 may be routed through either or both of the core networks 506, 507.The NAS entity 534 a manages the protocol between the NAS entity 512 andthe NAS entity 513.

The RRC 508 a is an entity that controls one or more RATs which may bemanaged by a corresponding RRC of the RAN 504, 505. For example, RRC 508a may control the connection between MRA WTRU 502 a and RRC 524 of RAN504 and the connection between MRA WTRU 502 a and RRC 525 of RAN 505.For example, the MRA WTRU 502 a may use a single RRC 508 a, which maymanage the RRC 525 on an air interface 517 on at least one frequencywhere LTE is deployed and simultaneously mange an RRC 524 on an airinterface 516 on at least one frequency used for a HSPA. In embodiments,the RRC 508 a may control the one or more RRC connections between theMRA WTRU 502 a and one or more RANs 504, 505, by using an RRC instancefor each of the RANs 504, 505.

FIG. 5B schematically illustrates an MRA WTRU 502 b, a NAS entity 534 b,and two RRC entities 508 b, 509 b, air interfaces 516, 517, RANs 504,505, core networks 506, 507, and PDN Network 509. The RRCs 508 b, 509 bare entities that control one or more RATs which may be managed by acorresponding RRC of the RAN 504, 505. The MRA WTRU 502 b may have oneRRC 508 b, 509 b per RAT, and a single NAS 534 b for one or more corenetworks 506, 507. For example, RRC 508 b may control the connectionbetween MRA WTRU 502 b and RRC 524 of RAN 504, where the RAT of RAN 504may be LTE, and the RRC 509 b may control the connection between MRAWTRU 502 b and RRC 525 of RAN 505, where the RAT of RAN 505 may be partof a UMTS/GPRS.

FIG. 5C schematically illustrates an MRA WTRU 502 c, NAS entities 534 c,535 c and RRC 508 c, air interfaces 516, 517, RANs 504, 505, corenetworks 506, 507, and PDN Network 509. The RRC 508 c is an entity thatcontrols one or more RATs which may be managed by a corresponding RRC ofthe RAN 504, 505.

The NAS entities 534 c, 535 c are entities that control the NAS layerprotocols 402. A single NAS entity 534 controls the NAS layer protocols402 between the MRA WTRU 502 c and a NAS entity of a single core network506, 507. For example, NAS 534 c may manage the NAS protocol between theMRA WTRU 502 c and the NAS 512 of core network 506, and NAS 535 c maymanage the NAS protocol between the MRA WTRU 502 c and the NAS 513 ofcore network 507. MRA WTRU 502 c may have more than two NAS entities 534c, 535 c with each NAS entity 534 c, 535 c managing a NAS layer protocol402 between the MRA WTRU 502 c and a core network 506, 507. The NASentities 534 c, 535 c may communicate with one another via connection540 to manage the multiple connections to different core networks 506,507. For example, the MRA WTRU 502 c may be connected to PDN 509. Thedata traffic from the connection to and from the PDN 509 may be routedthrough either or both of the core networks 506, 507. The NAS entity 534c may manage the traffic flow to and from the PDN 509 via core network506 with NAS 512. The NAS entity 535 c may mange the traffic flow to andfrom the PDN 509 via core network 507 with NAS 513. The NAS entities 534c, 535 c may communicate with one another via connection 540 tocoordinate the traffic to and from the PDN 509 via the two differentcore networks 506, 507. For example, the NAS entities 534 c, 535 c mayinteract and coordinate all or specific mobility and session managementprocedures. For example, the activation/modification/deactivation of anIP address/bearer by NAS entity 534 c, which may be a LTE NAS 535 cattached to core network 506 and communicating with NAS 512, may besignaled or communicated over connection 540 to NAS entity 535 c, whichmay be part of a UMTS/GPRS system and attached to core network 507 andcommunicating with NAS 513. In this way, all the NAS entities 534 c, 535c, may be updated with the current active IP addresses and bearers, orother mobility management parameters and security parameters.

FIG. 5D schematically illustrates an MRA WTRU 502 d, NAS entities 534 c,535 c and RRC connections 508 d, 509 d, air interfaces 516, 517, RANs504, 505, core networks 506, 507, and PDN Network 509. The NAS entities534 d, 535 d are entities that control the NAS layer protocols 402. Asingle NAS entity 534 controls the NAS layer protocols 402 between theMRA WTRU 502 d and a NAS entity of a single core network 506, 507. TheRRCs 508 d, 509 d are entities that control one or more RATs which maybe managed by a corresponding RRC 524, 525 of the RAN 504, 505.

FIG. 6 schematically illustrates an MRA WTRU 602 for determining whichcell to access for MRA operation. Illustrated in FIG. 6 is a MRA WTRU602, a user 650, information 632, a stored data 630, RANs 604 a, 604 b,core networks 606 a, 606 b, and PDN 609. As discussed above, a cell is ageographic region that is served by one or more base stations 614 a, 614b.

The MRA WTRU 602 may be configured as described above with a single NASentity 534 or multiple NAS entities 534, with a single RRC 508connection or multiple RRC 508 connections.

The MRA WTRU 602 may be configured to determine which cell to select forMRA operation. The MRA WTRU 602 may determine which cell to select forMRA operation prior to determining to initiate MRA operation or afterdetermining to initiate MRA operation. The MRA WTRU 602 may determine acell of a first RAT to establish a first connection for MRA operation,and may determine a cell of a second RAT to establish MRA operation, andmay, optionally, establish a second connection for the second RAT.

The MRA WTRU 602 may use signaling received over the air interface 616from the RAN 604, core network 606, PDN 609, or other network portion todetermine which cell to select for MRA operation.

The MRA WTRU 602 may select which cell to select for MRA operation basedon a public land mobile network (PLMN) that the cell is part of. Forexample, the MRA WTRU 602 may only select cells that are part of thePLMN that is part of a customer agreement between the user 650 and thePLMN.

The MRA WTRU 602 may select which cell to select for MRA operation basedon stored data 630. The stored data 630 may be stored locally as part ofthe non-removable memory 130 or the removable memory 132 of the MRA WTRU602, or the stored data 630 may be accessed by the MRA WTRU 602 over theair interface 616 where the stored data 630 is stored in a remotelocation such as data server (not illustrated), which may be part of theRAN 604, the core network 606, or other portion of the network.

The stored data 630 may be associated with a universal subscriberidentity module (USIM). The stored data 630 may indicate which cellssupport MRA operation. The stored data 630 may indicate which PLMNssupport MRA operation. The stored data 630 may include a list of PLMNsthat support MRA operation; a list of area identities that support MRAoperation; a list of closed group subscriber (CSG) identities thatsupport MRA operation; a list of eNodeB and RNC identities or othernetwork entities that support MRA operation; and a list of cellidentities that support MRA operation. The stored data 630 may includean indication of whether or not MRA operation is supported across cellsof different PLMNs, across cells of different area identifiers, acrosscells of different CSG identifiers, and across cells of different eNodeBand RNC identities, or across cells of other network entities.

The stored data 630 may include an indication of the RAT type and/orcategory of the RAT for PLMN identities, area identities, CSGidentities, eNodeB/RNC identities, and cell identities. The stored data630 may include an indication of whether or not a cell may be accessedto initiate and/or setup the MRA operation for PLMN identities, areaidentities, CSG identities, eNodeB/RNC identities, and cell identities.For example, the stored data 630 may include with a PLMN identity anindication of whether or not MRA operation is possible across cells ofdifferent PLMNs. As another example, the stored data 630 may include anindication of whether or not MRA support provided by a PLMN is based ona specific RAT type, and the stored data 630 may include an indicationof which other PLMNs the PLMN may conduct MRA operations with. Thestored data 630 may associate a RAT type for PLMN identities, areaidentities, CSG identities, eNodeB/RNC identities, and cell identities.

The MRA WTRU 602 may identify a cell for MRA operation by searching forcells that support MRA operation. The MRA WTRU 602 may determine whetheror not a cell supports MRA operation based on information 632 receivedover the air interface 616, and may, optionally, use stored data 630 inthe search. For example, the MRA WTRU 602 may exclude a cell based oninformation contained in the stored data 630 indicating that the celldoes not support MRA operation. The information 632 may be SystemInformation Broadcasting from a RAN 604 or core network 606 thatindicates whether or not one or more cells support MRA operation.

The search may be part of an initial cell selection procedure the MRAWTRU 602 is performing, or part of a cell re-selection procedure. TheMRA WTRU 602 may only search for cells that support MRA operation whenthe MRA WTRU 602 is in a particular mode such as idle. The MRA WTRU 602may search over one or more RAT either sequentially or simultaneously.The MRA WTRU 602 may search over one or more cells either sequentiallyor simultaneously.

The MRA WTRU 602 may store the results of the search in stored data 630and determine whether or not a cell supports MRA operation based on thestored search results. The MRA WTRU 602 may search for and find at leastone cell that supports MRA operation for two or more RAT types beforeattempting to initiate MRA operation. The MRA WTRU 602 may attempt toinitiate MRA operation either independently or based on a requestreceived from over the air interface 616 from the RAN 604 or corenetwork 606, or other network portion such as the PDN 609.

The MRA WTRU 602 may repeat the search one or more times to identify oneor more cells for MRA operation. The MRA WTRU 602 may search and findone or more cells that support MRA operation and rank the found cells.For example, the cells may be ranked according to ranking data stored inthe USIM configured stored in the stored data 630.

The MRA WTRU 602 may perform the search by monitoring messages from acell, and determining whether or not the cell supports MRA operationbased on the monitored messages. For example, a system informationbroadcasting message received from a cell may include a MRA indicator.In other examples, the MRA WTRU 602 may monitor information 632 to andfrom another MRA WTRU 602 and the cell to determine whether or not thecell supports MRA operation.

The MRA WTRU 602 may perform the search by attempting to initiate MRAoperation on a cell and determine based on the response from the cellwhether or not the cell supports MRA operation.

The MRA WTRU 602 may perform the search based on a USIM configuration instored data 630. For example, the stored data 630 may indicate that onlya finite set of cells should be searched, that the search should only berepeated a predetermined number of times, that a predetermined amount oftime should occur between searches, or that the search should only beperformed for a predetermined amount of time. In another example, thestored data 630 may indicate that a search should only be performeduntil the cells needed for the MRA operation are found.

The MRA WTRU 602 may perform the search by attaching to a core network606 via a first cell 604 a and then communicating with the communicatingwith network portions that indicate whether or not another cell supportsMRA operation. For example, the MRA WTRU 602 may attach to NAS 612 a ofcore network 606 a via first cell 604 a over a first RAT and receive anindication from NAS entity 612 a which may be an MME, SGW, PGW, SGSN, orPCRF, or other core network 606 a entity, that another cell with adifferent RAT supports MRA operation. The MRA WTRU 602 may perform thesearch by attaching to a NAS 612 a via a cell that does not support MRAoperation and requesting or receiving information 632 to aid in thesearch for cells that support MRA operation. The MRA WTRU 602 mayperform the search by attaching to NAS 612 a via a first cell over afirst RAT that support MRA operation, and then search for a second cellover a second RAT that supports MRA operation. The MRA WTRU 602 may havepreference for attaching via cells that support MRA operation, eventhough the MRA WTRU 602 does not at the time of attaching intend toinitiate MRA operation.

The MRA WTRU 602 may receive information 632 from the network indicatingsupport for MRA operation. The information 632 may be received from abroadcast signal such as System Information, BCCH, or System InformationBlock (SIB). The information 632 may be dedicated signaling such as froma NAS message or a RRC message. The following are some examples ofdedicated signaling messages that may include the information 632:attach accept; session management messages such as bearer resourceallocation, and bearer resource allocation modification procedures; and,PDN connectivity request messages such as activate default/dedicatedbearer, and modify bearer context.

The information 632 may be received from a dedicated signaling messagesuch as an RRC 624 message such as RRCConnectionReconfiguration message.The dedicated signaling message may be a request to configure to MRAoperation. Other examples of messages that may include the information632 are OMA DM, OTA, or ANDSF.

The information 632 may be received in a paging message. The information632 may include an indication for support of MRA operation for PLMNidentities, area identities, CSG identities, eNodeB/RNC identities, cellidentities, for cells of the Tracking Area, for cells of the RoutingArea, for cells of the Location Area, for a specific core network nodesuch as an MME, SGSN, or MSC/VLR. For example, the information 632 mayindicate that the current cell from which a system information broadcastis received by the MRA WTRU 602 supports MRA operation. Additionally,the information 632 may include an indication of whether or not MRAoperation is supported for different PLMNs from the current PLMN.

The information 632 may indicate a preference or preferred order for theMRA WTRU 602 to use the cells that support MRA operation. The preferenceor preferred order may be indicated by the order that the cells thatsupport MRA operation are sent to the MRA WTRU 602. The information 632may not indicate whether or not the MRA WTRU 602 is permitted to use MRAon the cells that support MRA operation. The MRA WTRU 602 may receive anindication of whether the MRA WTRU 602 may use the cells that supportMRA operation in different information 632 that may come from, forexample, a network entity over a NAS protocol.

The MRA WTRU 602 may display one or more of the following to the user650 whether MRA is supported for the currently attached cell, for thecurrent PLMN, for neighboring cells, and whether or not MRA operationcould be initiated. The MRA WTRU 602 may provide an interface to theuser 650 that enables the user 650 to turn on or off the MRA WTRU 602MRA operation. The MRA WTRU 602 may provide an interface to the user 650that enables the user to turn on or off the MRA WTRU 602 searching forcells that support MRA operation. The MRA WTRU 602 may provideinformation relating to MRA operation to upper layers such as an ANDSFclient that may require an indication of whether or not MRA operation issupported to apply some mobility policies.

The MRA WTRU 602 may either autonomous request MRA operation or the MRAWTRU 602 may initiate MRA operation in response to receiving a requestfrom a network entity to enter MRA operation. For example, the MRA WTRU602 may request a connection to an APN, which may then initiate MRAoperation and request that the MRA WTRU 602 enter MRA operation. Otherexamples include the MRA WTRU 602 requesting a specific QoS, IP address,or service such as CS call, SMS, or SS, where in each of these cases anetwork entity may determine that the MRA WTRU 602 should enter MRAoperation.

The MRA WTRU 602 may determine to enter MRA operation after havingidentified one or more cells that supports MRA operation for two or moredifferent RATs. The MRA WTRU 602 may determine to enter MRA operationbased on any of the following: if the one or more cells are of the samePLMN; if the PLMN of the one or more cells is RAT-specific; if the CSGidentity for the one or more cells indicates support for MRA; if the oneor more cells are of different PLMNs, but the different PLMNs supportinter PLMN support for MRA.

The MRA WTRU 602 may initiate MRA operation based data in the storeddata 630, which may be a configuration. The MRA WTRU 602 may initiateMRA operation based on one or more of the following: always initiaterequest MRA operation; initiate MRA operation based on the MRA WTRU 602being in MRA operation when the MRA WTRU 602 was last used; in responseto a user 650 requesting MRA operation; in response to a user 650changing a configuration of the MRA WTRU 602; and, in response to a newservice being initiated in response to satisfying an action of a user650.

The MRA WTRU 602 may initiate MRA operation by a network entity mayrefuse the MRA operation. For example, an HSS entity may deny MRAoperation based on subscription information related to the MRA WTRU 602in the core network 606. The MRA WTRU 602 may initiate MRA operationaccording to one or more of the following: in an ATTACH procedure to afirst RAT indicating a second RAT; a dedicated NAS procedure such asmobility or session management; when requesting additional radio bearerresources; and, when requesting a service such as voice service and thefirst RAT does not support the CS Voice service.

The MRA WTRU 602 may initiate MRA operation during an RRC based request.For example, the MRA WTRU 602 may initiate a request to the network forMRA operation for a second RAT during the RRC connection establishmentprocedure on a first RAT. For example, upper layers of the MRA WTRU 602may request routing of MRA-related messages such that a NAS message mayinclude a MRA container destined to a core network entity associatedwith a second RAT (e.g., a DedicatedInfoNASOtherRAT informationelement).

For example, the MRA WTRU 602 may request the establishment of Defaultand Dedicated bearers which may trigger an RRC message that requestssetup of MRA operation, e.g., when an Initial Context Setup/RAB and/orSetup/RAB Modify leads to a reconfiguration of the RRC connection.

The MRA WTRU 602 may transmit the request for MRA operation on anexisting RRC and/or NAS connection. When the WTRU has transmitted arequest for MRA, it may monitor paging in a cell of a second RAT. Whenpaging is received from the cell of the second RAT, the MRA WTRU 602 mayinitiate an initial access to the second RAT for MRA operation using theradio resources of the concerned cell. In one example, the pagingrequest from the second RAT may be for a CS voice service.

FIG. 7 schematically illustrates the WTRU 602 receiving a message fromthe network to initiate MRA operation. FIG. 7 illustrates an MRA WTRU602, an AS 604, and a NAS 606. AS 604 represents that the message isoriginating from a network entity using an AS layer protocol 404 asdiscussed in conjunction with FIG. 4. NAS 606 represents that themessage is originating from a network entity using a NAS layer protocol406 as discussed in conjunction with FIG. 4.

The MRA WTRU 603 may initiate MRA operation 705 in response to receivinga message 702, 703 from the network to initiate MRA operation. Themessage 702, 703 from the network may be in response to a message 701sent from the MRA WTRU 603 to the network. The message from the networkmay be either from an entity using an AS 604 layer protocol or a NAS 606layer protocol.

For example, the MRA WTRU 603 may be attaching to a core network via acell of a first RAT with message 701, and the network may then send aNAS based message 702 requesting that the MRA WTRU 603 initiate MRAoperation on a second RAT. The NAS based message 702 may be from a corenetwork 606 entity relating to mobility management or sessionmanagement. The core network 606 entity may have received the message701. The MRA WTRU 602 may then initiate MRA operation 704 in response tothe NAS based message 702.

As another example, the MRA WTRU 603 may be in an RRC connectionestablishment or reconfiguration procedure for a cell of a first RATwith message 701 being part of the establishment or reconfigurationprocedure, and the network may then send an AS based message 703requesting that the MRA WTRU 603 initiate MRA operation on a second RAT.The MRA WTRU 602 may then initiate MRA operation 704 in response to themessage 703.

As another example, the MRA WTRU 603 may have registered with thenetwork and have indicated that the MRA WTRU 603 supports MRA operation.The MRA WTRU 603 may have received a configuration for MRA operation, oran indication from the network that MRA operation is supported. Thenetwork may then send an AS based message 703 that may be a pagingmessage that indicates to the MRA WTRU 603 to enter MRA operation. TheMRA WTRU 602 may then initiate MRA operation 704 in response to themessage 703.

As another example, the MRA WTRU 602 may have registered with thenetwork and have indicated that the MRA WTRU 602 supports MRA operation.The network may then send an AS based message 703 that may be a pagingmessage that indicates to the MRA WTRU 602 to enter MRA operation. Thepaging message may have originated from a network entity over NAS 606protocol. The MRA WTRU 602 may then initiate MRA operation 704 inresponse to the message 703.

In another example, the MRA WTRU 603 receives an AS based message 703that may be a paging message 703 in the cell of a first RAT. When theMRA WTRU 602 receives the paging message 703, the MRA WTRU 602 may beregistered with the core network 606, and may have indicated that theMRA WTRU 602 supports MRA operation. The MRA WTRU 603 may not have anactive RRC connection. The MRA WTRU 602 may then initiate MRA operation704 in the first cell in response to the message 703.

As another example, the MRA WTRU 603 receives an AS based message 703that may be a paging message 703 in the cell of a second RAT. When theMRA WTRU 602 receives the paging message 703, the MRA WTRU 602 may beconnected to at least a first RAT, or the MRA WTRU 602 may have receiveda paging message 703 in the first RAT, and not yet have connected to thefirst RAT. The MRA WTRU 602 may then initiate MRA operation 704 in thesecond cell in response to the message 703.

As another example, the MRA WTRU 602 may have an established RRCconnection, e.g., using either a EUTRA cell or a UTRAN/GPRS cell. Themessage 701 may be part of the establishment of the RRC connection. TheMRA WTRU 603 receives an AS based message 703 that may be initiated by aRAN entity such as eNodeB or NodeB, or RNC. The MRA WTRU 602 may theninitiate MRA operation 704 in the second cell in response to the message703.

As another example, the MRA WTRU 602 may indicate support for MRAoperation, for example as part of the MRA WTRU 602 capabilityinformation exchange. The message 701 may be part of the indication ofsupport for MRA. The MRA WTRU 603 receives an AS based message 703 thatmay be initiated by a RAN entity such as eNodeB or NodeB, or RNC. TheMRA WTRU 602 may then initiate MRA operation 704 in the second cell inresponse to the message 703.

As another example, the MRA WTRU 602 may request an RRC connection andset the establishment cause to a value. For example, a new establishmentcause may be defined to indicate request for MRA operation. Thisestablishment cause may be provided by the upper layers (e.g., NAS) as aresult of upper layer triggers to initiate MRA operation. The message701 may be part of the request for an RRC connection. The MRA WTRU 603receives an AS based message 703 that may be initiated by a RAN entitysuch as eNodeB or NodeB, or RNC. The MRA WTRU 602 may then initiate MRAoperation 704 in the second cell in response to the message 703.

As another example, the MRA WTRU 602 may send an establishment cause as“mobile originated (MO) CS call”, “mobile terminated (MT) CS call”, “MOCS call with ongoing packet switched (PS)”, or “MT CS call with ongoingPS.” The message 701 may be part of the sending of the establishmentcause. The MRA WTRU 603 receives an AS based message 703 that may beinitiated by a RAN entity such as eNodeB or NodeB, or RNC. The MRA WTRU602 may then initiate MRA operation 704 in the second cell in responseto the message 703.

In examples, the MRA WTRU 602 may be camping in a second cell with asecond RAT, and may receive an AS based message 703 as a paging message703 from the second RAT. For example, the MRA WTRU 602 may be connectedto a first RAT. The MRA WTRU 602 may then initiate MRA operation 704 inthe second cell in response to the message 703 to initiate connection tothe second RAT. In examples, the MRA WTRU 602 may receive a handoverrequest to move to a different cell for the second RAT such as a cellthat has a measurement report that indicates the connection should begood for the MRA WTRU 602.

As part of message 702 or message 703, or as a separate message, the MRAWTRU 602 may receive an RRC configuration that may include measurements(e.g., inter-RAT) related to a frequency for a second RAT on which theWTRU is not currently connected. In examples, the measurement report isassociated with a prohibit timer. For example, a measurement report thatis triggered by a concerned event may start the timer and, while thetimer is running, the MRA WTRU 602 may not be allowed to trigger furthermeasurement reports for the concerned event. In examples, themeasurement report is associated with some rule to restrict itsapplicability, for example, it may trigger a measurement report onlyduring periods for which the MRA WTRU 602 is actively scheduled. Forexample, a LTE eNodeB may configure inter-RAT measurements for UTRAfrequencies.

In examples, as part of message 702 or message 703, the MRA WTRU 602 mayreceive a configuration for a procedure by which the MRA WTRU 602 maydetect the proximity of a cell that supports MRA operation on afrequency of a second RAT.

In examples, the MRA WTRU 602 either before or after receiving message702, 703 may transmit a measurement report that indicates that the radiolink quality measured for a cell of a second RAT is suitable for MRAoperation. In examples, the MRA WTRU 602 may only transmit the measurereport if the MRA WTRU 602 has determined that the cell of a second RATis suitable for MRA operation.

In examples, a RAN entity such as eNodeB or NodeB, or RNC, may determinethat the MRA WTRU 602 should initiate MRA operation, and the RAN entitymay initiate and/or request the core network association for MRAoperation for example to the MME and/or to the SGSN. The core networkassociation may be performed according to the principles describedherein. So, even though an entity that may be part of the AS protocoldetermines the MRA WTRU 602 should initiate MRA, the message received bythe MRA WTRU 602 may be a NAS based message 702.

In examples, after message 704, the MRA WTRU 602 may be configured by aNAS entity or RRC entity for MRA operation. For example, a combinedattach procedure as described below may be used.

When the WTRU identifies at least one suitable EUTRAN cell that supportMRA operation and possibly also at least one suitable UTRAN cellcandidate. Possibly, during cell search/cell selection.

FIG. 8 is a flow diagram of an example combined attach procedure 800 foran eUTRA (LTE) RAT. The WTRU 802 may initiate a combined attachprocedure based on any of the reasons disclosed herein.

In 850 of FIG. 8, an WTRU 802 may send an attach request message toregister the WTRU 802 for MRA operation on two or more RATs (forexample, EUTRAN and UTRAN/GERAN) using an EUTRAN (MRA-capable) cell.

New attach types for the attach request for MRA may be added to standardattach types. The new attach types may include one or both of thefollowing: Type 1) for combined EPS/international mobile subscriberidentity (IMSI) with GPRS (i.e., register for LTE PS and for UTRAN/GERANPS/CS), e.g., a “Combined EPS/GPRS/IMSI attach” type; or, Type 2) forcombined EPS and GPRS (i.e., register for LTE PS and for UTRAN/GERANPS), e.g., a “Combined EPS/GPRS attach” type.

A WTRU 802 may use, e.g., one of the above types in the attach requestfor MRA operation to indicate to the network that it can attach to bothRAT networks with desired traffic type domains, e.g., using GPRS/EPS forUTRAN PS and LTE PS or using GPRS/IMSI/EPS for UTRAN PS/CS and LTE PS.See FIG. 23 for additional examples of type information elements.

In addition, if the selected cells of the different RATs are associatedwith different CSG and/or PLMN, e.g., the PLMN of the EUTRAN celldiffers from that of the UTRAN cell, the WTRU 802 may additionallyinclude the UTRAN PLMN identity in the attach request message.

In examples, the WTRU 802 may include in the attach request message 850a list of PLMN identities from the other RAT, e.g., as derived from aPLMN search and possibly listing all the PLMNs the WTRU 802 can see forthe other RAT. In examples, the WTRU 802 selects a PLMN for the otherRAT and provides the selection to the MME. In examples, the WTRU 802provides a priorities list of PLMNs for the other RAT and provides theprioritized list to the MME. The MME may then chose an MSC/VLR based onthe prioritized list and if an attach fails, then the MME may choseanother MSC/VLR based on the prioritized list to attempt to attach to.

In 852 of FIG. 8, EUTRAN and WTRU 802 authentication and key agreementprocedures may be carried out among the MME, the HSS/HLR and the WTRU802. The attaching WTRU 802 may be thoroughly authenticated.

In 854 of FIG. 8, the mutual root key KASME between the MME and the WTRU802 may be agreed on such that subsequent security keys for NAS and ASin EUTRAN may be separately derived from the KASME at the WTRU 802 andthe MME for the operations on the LTE RAT.

In 856 of FIG. 8, the WTRU 802 attaches to EUTRAN. In examples, attachprocedure 856, may be performed as follows. If there are active bearercontexts in the MME 806 for the WTRU 802, which may be the case if theWTRU 802 re-attaches to the same MME 806 without having properlydetached before, the MME 806 may then instruct SGW 808, PGW 812, and thePCRF (not illustrated) to delete these bearer contexts. The MME 806 mayinitiate a location update procedure toward the HSS 814, which mayresult in the deletion of the MM (mobility management) and bearercontexts from the old MME 806, if need be as well as the deletion of anyactive bearer of this WTRU 802 from SGW 808, PGW 812, and the PCRF. TheMME 806 initiates toward the SGW 806 (serving GW), the PGW 812 (PacketData Network GW) and the PCRF the activation of the new bearer contextsas required by the attach request message content.

The MME 806 updates the HSS 814 that the WTRU 802 is now under itsservice and gets the WTRU 802 subscriber information from the HSS 814.The MME 806 then creates a PDN connection for the WTRU 802 towards theSGW 808 or PGW 812 since IP address allocation happens as part of theattach procedure in LTE.

If the attach type includes an IMSI attach, the MME 806 may allocate anLAI, (e.g., by converting from the TAI included in the LTE attachrequest message), for the WTRU 802. The selected PLMN ID may be includedin the new LAI that may be sent to the MSC/VLR. 810. If multiple PLMNsare available for the CS domain, the MME 806 may perform selection ofthe PLMN for CS domain based on selected PLMN information received fromthe WTRU 802, current TAI, old LAI and operator selection policies onpreferred RAT for CS domain.

In 858 of FIG. 8, the MME 806 may then send a Location Update Request(new LAI, IMSI, MME name, Location Update Type, and an indication forMRA operation) message to the MSC/VLR 810 to prepare the MSC 810 for CSservices for the attaching WTRU 802. The MSC/VLR 810 may create anassociation with the MME 806 by storing the name of the MME 806. The VLR810 may check the WTRU 802 for its regional subscription or accessrestrictions for the LA. The MME 806 may select the MSC 810 to send theLocation Update Request based on a selected PLMN, which may be receivedfrom the WTRU 802, and based on PLMN policies from the WTRU 802.

In 860 of FIG. 8, the MSC 810 may perform a location updating procedurein the CS domain with the HLR/HSS 814. In 862 of FIG. 8, the MSC/VLR 810may then respond with a location update accept message (with the VLR 810assigned TMSI for the WTRU 802 to operate in UTRAN CS domain, i.e., inMRA mode) to the MME 806. Optionally, the MSC/VLR 810 may accept theIMSI attach for CS service via MME 806 but not for MRA. The MSC/VLR 810may not accept MRA based on, for example, subscription information fromthe HSS 814. Thus, the location update accept message 862 returned tothe MME 806 indicates if the IMSI attach is for MRA or for current CSservices such as CSFB or SMS-only. This information is also passed tothe WTRU 802 in the attach accept message.

If rather than a location update accept message 862, the MSC/VLR 810sends a location update rejection to the MME 806, then the MME 806 mayselect another MSC/VLR 810 based on a list of PLMNs for the CS domainreceived from the WTRU 802. There may not be another MSC/VLR 810available. The MME 806 may then perform a location update procedure asfollows.

If the rejection code is “Roaming is not allowed in the selected PLMN”,the MME 806 may reselect the MSC/VLR 810 in another PLMN for CS domain,may allocate a LAI for the selected PLMN and may derive a new MSC/VLR810 from the LAI as specified in 856 of FIG. 8 and may perform alocation update procedure with the new MSC/VLR 810 again.

If the rejection code is “Access is not allowed in the selected locationarea”, the MME 806 may allocate another LAI for the other RAT (i.e.,GERAN or UTRAN), may derive the new MSC/VLR 810 from the LAI, and mayperform location update with the new MSC/VLR 810 again. Alternatively,the MME 806 may choose another MSC/VLR 810 without performing any LAIallocation.

If the attach type includes a GPRS attach for UTRAN PS, and if multiplePLMNs are available for the PS domain, the MME 806 may perform selectionof the PLMN for PS domain based on selected PLMN information receivedfrom the WTRU 802, current TAI, old LAI and operator selection policieson preferred RAT for PS domain. The MME 806 may perform the aboveselection in a corresponding way for CS registration. The MME 806 maythen select or find a relevant SGSN 804 for the chosen UTRAN PLMN andsend a new message, which may be called “Context Indication”, and whichmay contain one or more of the following the MM Context, the EPS BearerContexts, the Serving GW signaling address, TEID, WTRU InformationChange Reporting Action, CSG Information Reporting Action, WTRU TimeZone, and ISR Supported. The new message may be used to make theMR-ACCESS association between the two RATs (LTE & UTRAN) on the MME 806and the SGSN. The SGSN 804 may save the MME ID and address for laterMR-ACCESS interaction.

The MME 806 or another controlling entity may derive and pass thecorresponding UTRAN security parameters to the SGSN in the new MR-ACCESSassociation message, “Context Indication,” to achieve theone-attach-for-two-RAT goal.

In 864 of FIG. 8, the WTRU 802 and the MME 806 may derive aconfidentiality key CK′, and an integrity key IK′ from the KASME using aone-way key derivation function KDF. The input to the KDF may be theselected NAS uplink COUNT value of the current EPS key security contextor a count value specifically for MR-ACCESS. For example, the average ofthe sum of the downlink and uplink NAS count values rounded up or downfor PO parameter may be the input to the KDF function.

In 866 of FIG. 8, the WTRU 802 and MME 806 may derive the value of KSIfrom the eKSI (i.e., KSI=eKSI). In another example, if there exists anold UTRAN KSI (carried to the MME 806 via the attach request 850) at theWTRU UTRAN security context prior to this attach procedure, then theKSI=old KSI+1 or the KSI=eKSI+1.

In 868 of FIG. 8, the MME 806 may transfer CK′, IK′ with KSI to the SGSNin, for example, the Context Indication message. The target SGSN mayreplace one or more of the stored parameters CK, IK, KSI, with CK′, IK′,and the KSI received from the MME 806. The WTRU 806 may replace one ormore stored parameters CK, IK, KSI with CK′, IK′, KSI in both ME andUSIM. STARTps may comply with the rules of 3GPP. The MME 806 may use CK′and IK′ to derive the GPRS Kc using a c3 function. The MME 806 mayassign the eKSI value (associated with CK′ and IK′) to the GPRS CKSN.The MME 806 may update the USIM and ME with the GPRS Kc and GPRS CKSN.

In 870 of FIG. 8, the MME 806 may update the HSS/HLR 814 on the statusof the SGSN 804 with one or more of SGSN number, SGSN address, IMSI,IMEISV, and update type. The HSS/HLR 814 may also send to the SGSN oneor both of the subscription data of the WTRU 802 and the CSGsubscription data for the PLMN.

In 872 of FIG. 8, the new SGSN 804 may send a new message, which may becalled a “Context Acknowledge” message, to the MME 806 indicating theGPRS attach accept to the MME 806 with UTRAN operating parameters forthe WTRU 802 embedded in the context acknowledge message. This may alsobe part of the MRA association between the two network controllingnodes.

In 874 of FIG. 8, the method may continue with an attach procedure. Forexample, the attach procedure may include an accept message. Inexamples, the attach procedure may be performed as follows. The MME 806sets up a context for the WTRU 802 at the eNodeB (not illustrated),which reconfigures the WTRU 802 with radio bearer for user plane data.The MME 806 coordinates connection establishment between the eNodeB andthe SGW 808 for user plane bearer on the S1 interface. The WTRU 802 isthen ready to send/receive IP data.

In examples, the attach procedure may be as follows. The MME 806 sendsthe initial context setup request message including the attached acceptmessage to the eNodeB (not illustrated.) The eNB then reconfigures theWTRU 802 with new bearers according to the instruction from the MME 806by sending to the WTRU 802 the RRC connection reconfiguration messagealong with the attach accept message. The eNodeB sends the initialcontext response message to the MME 806. The WTRU 802 sends a directrransfer message to the eNodeB, which includes the attach completemessage. The attach complete message may include one or more of EPSbearer identity, NAS sequence number, or NAS-MAC. The eNodeB forwardsthe attach complete message to the MME 806 in an uplink NAS transportmessage. Upon reception of both messages, the initial context responsemessage and the attach complete message, the MME 806 triggers the modifybearer procedure toward the SGW 808 which triggers the modify bearermethod toward the PGW 812. Upon the completion of the method with thereception of the modify bearer response message by the MME 806, the MME806 notifies the HSS 814 with the APN and the PGW 812 identity if thePGW 812 selected by the MME 806 is different from the one identified bythe HSS 814 to the MME 806.

The attach accept message may be updated to support the MRA attach type.For example, new fields for GPRS attach may be added as disclosed inconjunction with FIG. 24 with the contents of the attach accept messagediscussed in conjunction with FIG. 25.

In examples, the MME 806 may search for the MSC 810 and the SGSN 808 inanother PLMN, and may use the other-PLMN or the other-LAI/RAI or othercell identities included in the attach request message 850 for thisprocedure.

FIG. 9 is schematic illustration of a flow diagram of another example ofa combined attach method from an eUTRA (LTE/EPS) RAT where a PDP contextis created for the WTRU in the GPRS/UMTS domain and in the EPS domain.The WTRU 902 may attach to two or more different entities of two or moredifferent core networks with two or more different RATs. In the exampleof FIG. 9, both an EUTRAN and UTRAN are attached to through one attachrequest method in the EUTRAN network. In the example of FIG. 9, the WTRU902 may attach to an MME 906 and a MSC/VLR 910. In examples, one or moreUTRAN parameters used by the WTRU 902 are included in the attach requestmessage 950 to the EUTRAN. The UTRAN parameters included with the attachrequest message 950 may include one or more of old UTRAN WTRU-IDs suchas the old TMSI or old P-TMSI values, the old UTRAN security values suchas the old-KSI value, the current UTRAN area-IDs, found cell-IDs andoptionally the other RAT, which is UTRAN in this example, and PLMN-ID.In this example, the WTRU 902 may use one active primary PDP Context foreach RAT for MRA operation.

In 950 of FIG. 9, the WTRU 902 may include an attach type with theattach request 950. For example, the attach type may be one describedabove such as “Combined EPS/GPRS/IMSI attach” or “combined EPS/GPRSattach”. The attach request 950 may indicate that the WTRU 902 canattach to both RAT networks and indicate the desired traffic typedomains. For example, the attach request 950 may indicate that GPRS/EPSshould be used for the UTRAN PS, and LTE PS, respectfully, or thatGPRS/IMSI/EPS should be used for UTRAN PS/CS and LTE PS, respectfully.The WTRU 902 may additionally embed an “UTRAN Activate PDP context”request message in the attach request 950. A more detailed example ofsuch type information element definition is disclosed below.

In FIGS. 9, 952, 954, 956, 958, 960, 962, 964, and 966 may be similar to852, 854, 856, 858, 860, 862, 864, and 866 in FIG. 8.

In FIG. 9, 968 is similar to 868 of FIG. 8. Additionally, the MME 906may include one or more of the following in the context indicationmessage sent to the SGSN 904: the address of the SGW 908, address of thePGW 912, and the “activate PDP context request”. The WTRU 902 may embedan “activate PDP context request” in the attach request 950, when theattach type included in the attach request 950 includes a GPRS attach.

In FIG. 9, 970 may be similar to 849 of FIG. 8. Additionally, the SGSN904 may update with HSS/HLR 914. The SGSN 904 may store the ID andaddress of the MME 906.

In 972, 974, 976, and 978 of FIG. 9, the SGSN 904 may activate a PDPcontext. In 980, the SGSN 904 may embed “attach accept and activation ofa PDP context.” in the context ack 980. In FIG. 9, 982 may be similar to874 of FIG. 8. The attach accept message of 982 may include additionalcarrier UTRAN attach status. In 982, the WTRU 902 may receive an attachaccept message from the MME 906. The attach accept message may indicatewhether or not the attach procedure for MRA operation is successful. Theattach accept may include GPRS registration parameters such as P-TMSI orGPRS security parameters. These parameters may be used by the WTRU 902to access GPRS services in SGSN 904.

The LTE attach accept message may include one or more UTRAN operatingparameters such as the GPRS attach accept message that could be used bythe WTRU for subsequent MRA operation. The LTE attach accept message mayinclude an information element related to UTRAN such as a “UTRAN attachstatus” IE. See FIG. 24 for additional examples of IEs.

In examples, the WTRU 902 may also perform an attach procedure toregister with the MME 906, SGSN 904, and MSC/VLR 910. For example, theWTRU 902 can indicate in the attach type 950 that the registration is tobe done with the MME 906, SGSN 904, and MSC/VLR 910. The WTRU 902 mayinclude all the necessary parameters as described herein for thedifferent registrations. In examples, the registrations can be carriedout in different orders. The registration to the MME 906, for example,then CS registration to the MSC/VLR 910, and then PS registration to theSGSN 904.

In the examples described herein, a WTRU 902 communicates with an MME906, which then initiates a registration towards an SGSN 904 or MSC/VLR910. In other examples, a WTRU 902 may perform a combined registrationwith an MSC/VLR 910 or SGSN 904. For example, the WTRU 902 may initiatea combined attach procedure towards an SGSN 904 and indicate in theattach type that the registration is for MRA and also indicate that theattach be done with the MME 906, the MSC/VLR 910 and SGSN 904. The SGSN904 may then initiate registration procedures towards the MME 906 andMSC/VLR 910 using the methods explained herein.

The WTRU 902 may receive an unsuccessful response for the combinedattach 950. In examples, the combined attach using the eUTRA may berejected by the by the network controlling entities. In examples, theresponse may consist of an attach accept message, possibly including oneor more UTRAN/RAT/PLMN-specific EMM cause values. In examples, the causevalue may be related to MRA operation. In examples, the response is fromthe UTRAN controlling entities such as SGSN 904 or MSC/VLR 910. Inexamples, the response is received due to the failure to create anassociation for MRA operation.

If the WTRU 902 receives an attach unsuccessful response, the WTRU 902may delete the corresponding UTRAN PMM/MM context. In examples, the WTRU902 may take one or more of the following actions, which may be based ona received EMM cause value. For EMM cause value: No Suitable Cells InLocation Area, the WTRU 902 may not initiate further MRA access with aUTRAN network (such as SGSN or MSC/VLR) or a UTRAN cell in the givenarea. For EMM cause value GPRS services not allowed in this PLMN, theWTRU 902 may update the list of PLMN for which it determines that MRAoperation is possible such that the PLMN in EMM cause may no longer beused for MRA operation. In examples, the PLMN may be removed from a listof PLMNs that support MRA. In examples, the WTRU 902 may not initiateMRA operation with UTRAN PS service in the given PLMN.

For EMM cause value CS domain not available, the WTRU 902 may notattempt a combined attach for MRA operation with CS service in thecurrent PLMN, current location area identity, or in with the current MME908. For EMM cause value MR-CS associate with UTRAN not supported, theWTRU 902 may retry initiation of MRA operation with a UTRAN cell in thecurrent PLMN or in a corresponding PLMN in case of a RAT-specific PLMN.For the following EMM cause values, EPS services not allowed, PLMN notallowed, and roaming not allowed in this tracking area, the WTRU 902 mayupdate the list of PLMNs for which it determines that MRA operation ispossible such that the PLMN in the EMM cause value may no longer be usedfor MRA operation. In examples, the PLMN may be removed from a list ofPLMNs that support MRA. In examples, the EMM cause may trigger the WTRU902 to perform a cell search. The WTRU 902 may perform a subsequentcombined attach method after receiving the failed attach response. Inexamples, the WTRU 902 may perform an attach method only to the UTRANnetwork.

For EMM cause code tracking area not allowed, the WTRU 902 may notinitiate a subsequent combined attach procedure using the EUTRAN networkin the same area. In examples, the WTRU 902 may subsequently initiate acombined attachment in a UTRAN network.

For any of the actions the WTRU 902 takes in response to receiving anEMM cause code, any of the following may be applicable. The WTRU 902 mayonly perform the action for a limited amount of time; the WTRU 902 maylimit the number of retries of the action to a predetermined number; theWTRU 902 may only perform the action while the WTRU 902 remainsgeographically in the current area; the action may only be performed ifthe WTRU 902 had autonomously initiated MRA access in contrast to thenetwork requesting the WTRU 902 initiate MRA operation; and the actionmay only be applicable until switching off the WTRU 902 or the UICCcontaining the USIM is removed.

FIG. 10 is a schematic illustration of a flow diagram of an example of acombined attach procedure from a UTRA (GPRS/UMTS/HSPA) RAT where a PDPcontext is activated in the EPS domain but no in the GPRS/UMTS domain.In examples, the WTRU 1002 may use a single attach message 950 toregister to a plurality of RATs. In examples, the WTRU 1002 may provideduring the registration process some information related to the networkresources that may be available for MRA operation at the location of theWTRU 1002 to the network. In examples, the WTRU 1002 may attach to boththe EUTRAN and UTRAN through one attach request action in the UTRANnetwork. This may be accomplished by including EUTRAN parameters used bythe WTRU 1002 in the attach request message. Example EUTRAN parametersthat may be included in the attach request are found cell-IDs and otherRAT such as EUTRAN with PLMN-ID. In the example illustrated in FIG. 10,the WTRU 1002 may use a single active primary PDP context for MRAoperation.

In 1050 of FIG. 10, a WTRU 1002 may send an attach request message 1050to register the WTRU 1002 for MRA operation on both RATs (for example,EUTRAN and UTRAN) using an UTRAN MRA-capable cell. In examples, the WTRU1002 sends the request message 1050 after identifying at least onesuitable UTRAN cell that supports MRA operation, and, in examples, atleast one suitable EUTRAN cell that supports MRA operation. Attach typesfor the attach request 1050 for MRA may be defined. The new attach typesmay include one or more of the following: a combined GPRS/EPS attachtype for combined GPRS/EPS, which may be register for UTRAN PS and forLTE PS; a combined GPRS/IMSI/EPS attach type for combined GPRS/IMSI withEPS, which may be register for UTRAN PS/CS and LTE PS; and a combinedIMSI/EPS attach type for combined IMSI/EPS, which may be register forUTRAN CS and LTE PS.

A WTRU 1002 include one of the above attach types in the attach request1050 for MRA operation to indicate to the network that it can attach toboth RAT networks with desired traffic type domains. In examples, theWTRU 1002 may include in the UTRAN attach request message 1050 an EUTRANPDN connectivity request to establish a default PDN connection asrequired for a WTRU 1050 attached to a EUTRAN network. See FIG. 28 foradditional information element examples.

In 1060 of FIG. 10, the EUTRAN performs an attach procedure. Inexamples, in 1060 of FIG. 10, the SGSN 1004 and WTRU 1002 performauthentication between one another. The SGSN 1004 notifies HSS/HLR 1014that the WTRU 1002 is under its service and downloads the subscriberinfo from the HSS/HLR 1014. The SGSN 1004 then registers the WTRU 1002towards the MSC/VLR 1010 which also downloads the subscriber info fromthe HLR 1014.

In examples, in 1060 of FIG. 10, the EUTRAN attach method may be asfollows. The SGSN 1004 may exchange an identification request andidentification response with an old SGSN, if there is one, and,subsequently, with the WTRU 1002. The SGSN and WTRU 1002 may perform anauthentication procedure. The equipment checking function may then beperformed.

If there are active PDP contexts in the SGSN 1004 for the WTRU 1002,which may be the case if the WTRU 1002 is re-attaching to the same SGSN1004 without having properly detached, then the SGSN 1004 deletes thesePDP contexts by sending delete PDP context request (TEID) messages tothe appropriate GGSNs. The GGSNs acknowledge with delete PDP contextresponse (TEID) messages. The SGSN 1004 may initiate location updateprocedures toward the HLR 1014 and the an old MSC/VLR 1010 to clean upthe old location, which may lead to the deletion of existing PDPcontexts in an old SGSN and a GGSNs. The HLR 1014 may send subscriptiondata from the HLR 1014 to the SGSN 1004 through the exchange of insertsubscriber data/insert subscriber data ack messages between the HLR 1014and the SGSN 1004. The SGSN 1004 may then initiate a location updateprocedure toward the MSC/VLR 1010 and the HLR 1014 to propagate the newlocation of the WTRU 1002 throughout the communications network.

In 1070 of FIG. 10, the SGSN 1004 may send a context indication message1070 to forward the context of the WTRU 1002 to the MME 1006. Thecontext indication message may include one or more of the followingparameters: the IMSI, mobile equipment (ME) identity, mobile stationinternational subscriber directory number (MSISDN), MM context, the EPSbearer context(s), the serving GW signaling address and the TEID(s),whether ISR supported, WTRU 1002 information change reporting action,CSG information reporting action, the WTRU 1002 time zone, the WTRU 1002core network capability, and WTRU 1002 specific DRX parameters. Inexamples, the method occurs once the WTRU 1002 is attached in UTRAN.Continuing with 1070 of FIG. 10, the SGSN 1004 may send the CK, IK, WTRU1002 security capabilities to MME 1006 such that security keys in UTRANmay be generated.

In 1072 of FIG. 10, the MME 1006 may generate a NONCE_(MME). In 1074 ofFIG. 10, the MME 1006 may calculate K′_(ASME)=KDF (CK, IK, NONCE). In1074 of FIG. 10, the MME 1006 may derive K_(NASint), K_(NASenc),K_(UPenc), K_(RRCint) and K_(RRCenc) from K′_(ASME) and may associatethose with a Key Set Identifier KSI_(SGSN). In examples, the MME 1006may select the same PGW 1012 and SGW 1008 as selected by SGSN 1004.

In 1078 of FIG. 10, the MME 1006 may send a create session request tothe SGW 1008 to create a PDN bearer. In examples, the MME 1006 mayselect a different SGW 1008 than the SGW 1008 selected by the SGSN 1004.The MME 1006 may select a different SGW 1008 in order to perform loadbalancing.

In 1088 of FIG. 10, the MME 1006 may send an acknowledgement context ACKto the SGSN 1004. The MME 1006 may include the K_(NASint), K_(NASenc),K_(UPenc), K_(RRCint) and K_(RRCenc), NONCE and KSI_(SGSN) in theacknowledgement message. In examples, the method may be performed aftera PDN bearer has been created.

In 1090 of FIG. 10, the attach accept message 1090 may includeadditional parameters to support MRA attachment. The additionalparameters may include one or more of the following: an EUTRAN attachaccept message. See FIG. 33 for additional examples of informationelements.

In FIGS. 10, 1080, 1082, 1084, and 1086 may be similar to stepsdisclosed herein. In examples, combined attach complete 1092 of FIG. 10,may be as follows. The WTRU 1002 sends an attach complete message to theSGSN 1004, which then sends a TMSI reallocation complete message to theMSC/VLR 1010. The combined registration with both the SGSN and MSC isthen complete.

In examples, combined attach complete 1092 of FIG. 10, may be performed.In examples, combined attach complete 1092 of FIG. 10, may be asfollows. If P-TMSI or VLR TMSI was changed, the WTRU 1002 acknowledgesthe received TMSI(s) by returning an attach complete message to the SGSN1004. If MSC/VLR TMSI was changed, the SGSN 1004 confirms the MSC/VLRTMSI re-allocation by sending a TMSI reallocation complete message tothe MSC/VLR 1010.

FIG. 11 is a schematic illustration of a flow diagram of another exampleof a combined attach procedure from a UTRA (GPRS/UMTS/HSPA) RAT where aPDP context is activated in the GPRS/UMTS/HSPA domain in addition to thePDP context activated in the EPS domain. The WTRU 1102 may attach toboth the UTRAN and EUTRAN through one attach request 1150 action in theUTRAN network. The attach request message 1150 may include one or moreof the following EUTRAN parameters: found cell-IDs and the other RATsuch as EUTRAN and the PLMN-ID. In this example, the WTRU 1102 may useone active PDP context for each RAT for MRA operation.

In 1150 of FIG. 11, the WTRU 1002 may include a UTRAN activate PDPcontext request and an EUTRAN PDN connectivity request in the combinedattach request 1150.

In examples, combined attach 1160 of FIG. 11, may be performed. Inexamples, combined attach 1160 of FIG. 11, may be as follows. The SGSN1104 obtains the WTRU 1102 context from an old SGSN (not illustrated),if there is an old SGSN. The SGSN 1104 notifies the HSS/HLR 1114 thatthe WTRU 1102 is under its service and downloads the subscriberinformation of the WTRU 1102 from the HSS/HLR 1114. The SGSN 1104 thenregisters the WTRU 1102 towards the MSC/VLR 1110 which also downloadsthe subscriber information of the WTRU 1102 from the HSS/HLR 1114.

In examples, combined attach 1160 of FIG. 11, may be as follows. Ifthere are active PDP contexts in the SGSN 1104 for the WTRU 1102, whichmay be the case if the WTRU 1102 re-attaches to the same SGSN 1104without having properly detached before, then the SGSN 1104 deletesthese PDP contexts by sending delete PDP context request (TEID) messagesto the appropriate GGSNs (not illustrated). The GGSNs acknowledges withdelete PDP context response (TEID) messages. The SGSN 1104 may initiatelocation update procedures toward the HLR 1114 and the old MSC/VLR toclean up an old location. This may result in the deletion of anyexisting PDP context in old SGSNs and GGSNs, and the sending of thesubscription data from the HLR 1114 to the SGSN 1104 through theexchange of insert subscriber data/insert subscriber data ack messagesbetween the HLR 1114 and the SGSN 1104. The SGSN 1104 may then initiatea location update procedure toward the MSC/VLR 1110 and the HLR 1114 inorder to propagate the new location of the WTRU 1102 throughout thenetwork.

In 1162 of FIG. 11, the SGSN 1104 may select an SGW 1108 and a PGW 1112.In examples, if a UTRAN activate PDP context request is embedded in theattach request 1150, the SGSN 1104 may initiate the PDP contextactivation procedure by sending a create session request to SGW 1108.

In 1170 of FIG. 11, the SGSN 1104 may initiate the attach procedure onEUTRAN after the PDP context is activated. In 1190 of FIG. 11, the SGSN1104 may include an EUTRAN attach accept and an UTRAN activate PDPcontext accept in the attach accept message 1190. See FIG. 35 foradditional examples of information elements.

The WTRU 1102 may receive an attach accept message from the UTRAnetwork. In examples, the attach accept message 1190 indicates whetheror not the attach procedure for MRA operation is successful. Inexamples, the attach accept message 1190 may include one or more EUTRANoperating parameter that are part of an EPS attach accept message. TheWTRU 1102 may use the one or more EUTRAN operating parameters forsubsequent MRA operation. In examples, the operating parameters mayinclude an information element related to EUTRAN such as an EUTRANattach status IE.

The WTRU 1102 may receive an unsuccessful response rather than an attachaccept 1190 in response to the combined attach request 1150. Inexamples, the combined attach request 1150 using the UTRA may berejected by the network controlling entities. In examples, the responsemay consist of an attach accept message that may include one or moreEUTRAN/RAT/PLMN-specific MM cause values. In examples, the cause valuemay be related to MRA operation. In examples, the response is from theEUTRAN controlling entities. In examples, the response is received dueto the failure to create an association for MRA operation.

If the WTRU 1102 receives an unsuccessful response, the WTRU 1102 maydelete the corresponding EUTRAN EMM context. In examples, the WTRU 1102may take at least one of the following actions in response to receivingan unsuccessful response.

If a received MM cause value is EPS services not allowed, PLMN notallowed, or Roaming not allowed in this tracking area, the WTRU 1102 mayupdate the list of PLMN for which it determines that MRA operation ispossible such that the WTRU 1102 may remove or change the status of thePLMN referenced in the MM cause. In another example, the WTRU 1102 maynot initiate MRA operation with the EUTRAN PS service in the PLMNreferenced in the MM cause.

If a received MM cause value is no suitable cell in tracking area, theWTRU 1102 may not initiate further MRA access with the EUTRAN network ora EUTRAN cell in the given area.

If a received MM cause value is GPRS services not allowed, or PLMN notallowed, or roaming not allowed in this location area, the WTRU 1102 mayupdate the list of PLMN for which it determines that MRA operation ispossible such that the PLMN referenced in the MM cause value may nolonger be used for MRA operation. In example, the referenced PLMN may beremoved from the list. In examples, the WTRU 1102 may trigger a cellsearch procedure to attempt to locate a new cell for MRA operation. Inexamples, the WTRU 1102 may perform a subsequent combined attachprocedure such that the WTRU 1102 may initiate the subsequent combinedattach procedure either using the EUTRAN network or the UTRAN network asits primary RAT for MRA operation. Alternatively, the WTRU 1102 maytrigger an attachment only in the UTRAN network.

If a received MM cause value is location area not allowed, or nosuitable cell in location area, the WTRU 1102 may not initiate asubsequent combined attach procedure using the UTRAN network in the samearea. In examples, the WTRU 1102 may subsequently initiate a combinedattachment in an EUTRAN network.

For any of the actions the WTRU 1102 takes in response to receiving anMM cause code, any of the following may be applicable. The WTRU 1102 mayonly perform the action for a limited amount of time; the WTRU 1102 maylimit the number of retries of the action to a predetermined number; theWTRU 1102 may only perform the action while the WTRU 1102 remainsgeographically in the current area; the action may only be performed ifthe WTRU 1102 had autonomously initiated MRA access in contrast to thenetwork requesting the WTRU 1102 initiate MRA operation; and the actionmay only be applicable until switching off the WTRU 1102 or the UICCcontaining the USIM is removed.

In examples, the WTRU 1102 may perform one attach procedure per RAT toenable MRA operation according to at least one of the methods describedherein.

Combined attach complete 1192 of FIG. 11 may be any of the examplesdisclosed in conjunction with 1092 of FIG. 10.

FIG. 12 is a schematic illustration of a flow diagram of an exampleRAT-specific attach procedure for a sequential operation.

The WTRU 1202 may perform one attach procedure for each RAT. The firstattach procedure may be initiated using the radio resources of the RATas selected by the WTRU 1202. The WTRU 1202 may initiate MRA operation.The attach procedures may occur sequentially, or concurrently. The WTRU1202 may also indicate in the subsequent attach that it is alreadyattached to a specific domain and may provide some parameters that canbe used for identifying the core network nodes. For example, the WTRU1202 may include GUMMEI or P-TMSI. Note that NAS entities in the corenetwork may also coordinate mobility and session management procedures,messages, and parameters.

For example, the WTRU 1202 may perform the RAT-specific attach method1200 of FIG. 12 according to at least one of the following.

The WTRU 1202 may perform 1250, 1252, 1254 and 1256 of FIG. 12 for theprimary attach according to a regular attach. The WTRU 1202 may includeadditional attach type for MRA operation in the attach request 1250. Forexample, the attach type may be one described in conjunction with otherfigures. In addition, the WTRU 1202 may include additional parameters inthe attach request message 1250 such as WTRU information, cellinformation, or area information applicable to another RAT. Theinformation may be acquired from a cell search, especially the area-IDinformation of the other RAT, which may be needed for the CN switchingnode to identify its counter-part on the other RAT. This information maybe used by the network controlling nodes to locate the networkcontrolling node of another concerned RAT, for example, an 1210 locatingthe corresponding MME 1208 for the purpose of establishing a corenetwork association.

In 1260, 1262, 1264 and 1266 of FIG. 12, the UTRAN/3G CN contextallocation procedure may perform the WTRU 1202 specific context andIP-address allocation with respect to the gateway node S-GW/P-GW 1212where the cross-RAT data re-routing is anchored. In embodiments, thetrigger for the default context allocation may originate from thenetwork controlling node such as SGSN 1210. For example, a GMM messagerequest PDP context activation message may be received by the WTRU 1202and the WTRU 1202 may still respond.

In 1268 of FIG. 12, the following may be completed: the UTRAN/3G CNregistration via attach, WTRU 1202 authentication and key agreement,WTRU 1202 default context/IP-address allocation. The WTRU 1202 mayeither remain in the connected mode or the WTRU 1202 may go to idlemode.

In 1272 of FIG. 12, the WTRU 1202 may indicate in the attach requestmessage 1272 that it requests to remain in the connected mode. Inembodiments, the WTRU 1202 may request, for example, in the attachrequest message, that the allocated IP-address is preserved for MRAoperation, which may extend the time limit of the 3G WTRU IP-addresspreservation.

The WTRU 1202 may perform a secondary attach procedure. In embodiments,only when the primary attach is complete, which may include thecompletion of the related WTRU 1202 context/IP-address allocationprocess. The secondary attach may be according to 1272, 1274, 1276,1278, 1280 and 1282 of FIG. 12, and may use the resources of thecorresponding RAT. The attach request message 1272 of the second attachmay include information related to the first attach accept method. Forexample, the second attach may include one or more of: the new WTRU 1202IDs, IP-address, the area-IDs, and security parameters.

In 1274 of FIG. 12, in examples, the WTRU 1202 authentication for thesecondary attach, for example with HSS, may be omitted. In examples, thesecurity keys may be generated in other steps (not illustrated) andbrought back to the WTRU 1202 via the attach accept message in 1256 ofFIG. 12. This may be the case when the attach methods of the respectiveRATs are performed sequentially.

In 1276 of FIG. 12, the secondary RAT controlling node, which is the MME1208 in this example, may initiate contact with the primary RATcontrolling node, which is the SGSN 1210 in this example, to establishthe MRA association. In examples, the SGSN 1210 may respond by sending amessage back to the MME 1208.

The core network association for MRA operation may enable bothcontrolling nodes, for example MME 1208 and SGSN 1210, to subsequentlyreceive, process, determine and send commands based on informationreceived regarding WTRU 1202 radio measurement changes, WTRU 1202serving cell changes, routing changes, tracking area changes, or networkload changes. The controlling nodes may monitor the informationregarding the WTRU 1202 to coordinate MRA operation for a given WTRU1202.

FIG. 13 is a schematic illustration of a flow diagram of an exampleRAT-specific concurrent attach method 1300. The WTRU 1302 may performthe RAT-specific attach procedure according to at least one of thefollowing.

The attach procedure on each RAT may be performed independently as shownin FIG. 13. The WTRU 1302 may perform the authentication and securitykey agreement procedures with the corresponding RAT part of the CNindependently. The WTRU 1302 may perform an additional PDP contextactivation with the UTRAN/3G CN to acquire and preserve a defaultIP-address. In another example, the SGSN 1310 may trigger the defaultcontext allocation by sending a GMM message request PDP contextactivation to the WTRU 1302 after it sends the attach accept message tothe WTRU 1302.

In the attach methods performed on each RAT for MRA operation, thefollowing additional information may be included in the attach requestto facilitate a simultaneous attach. The attach-type to indicate thenature of the attach for MRA operation. The information about the otherRAT, which may have been acquired from a cell search. The informationmay include the area-ID information of the other RAT, which is neededfor the CN switching node to identify its counter-part on the other RAT.The CN switching node may be MME 1308 or SGSN 1310 for the WTRU 1302.

A network may support MRA operation. MRA operation may include a WTRU1302 may being attached to a plurality of RATs and, in examples, acrossdifferent PLMNs. In this case, the network may establish some form ofassociation to support and coordinate MRA operation for a given WTRU1302. For example, the controlling entities in the core network mayperform at least one of the following.

The CN controlling node may initiate an MRA association. For example,the CN may use a sequence of request and response transactions toanother CN controlling node. In examples, the CN may initiate thesequence based on receiving an attach request from a WTRU 1302, or inexamples, based on receiving a request from a RAN controlling node suchas eNodeB for EUTRA, or NodeB or RNC for UTRA. In examples, thecontrolling node may be identified and located using informationincluded in the WTRU's 1302 initial attach request. For example, theinitial attach request may include one or more of the PLMN-ID, RAI, LAI,and Cell-IDs of the cell in the other participating PLMN.

Each CN controlling node 1308, 1310 may receive registration messages.For example, a CN controlling node 1308, 1310 may receive routing,tracking, or location area updates, and may receive measurement reportsfrom the WTRU 1302 over radio resources of the controlling node'scorresponding RAT. In examples, a WTRU 1302 may include the area changeor measurement results of a plurality of RATs in its normal area updateor measurement report for the RAN CN of the RAT.

The CN controlling node 1308, 1310 may determine that MRA operationrequires a change in routing path for a WTRU 1302. The CN controllingnode 1308, 1310 may command the attached WTRU 1302 via its own RATcommand path to establish the NAS context and, in examples, also NASconnection, as well as possibly the RAN connection for the reroutedtraffic.

In examples, the CN controlling node 1308, 1310 may page a WTRU 1302 inidle mode using the path of its corresponding RAT, independently ofanother CN controlling 1308, 1310 node of a different RAT.

In examples, the CN controlling nodes 1308, 1310 agree on which node isresponsible for paging the WTRU 1302 for a specific service. This mayalso be based on network policies or configurations. For example, duringa combined registration with an MME 1308 and MSC/VLR, based on at leastone of operator policies, network configurations, MME 1308 and MSC/VLRinteractions, or messaging.

In examples, each CN controlling node 1308, 1310 initiates the necessarypaging procedure. In examples, the MSC/VLR pages the WTRU 1302 in CSdomain with appropriate changes. For example, a new CN domain indicatorto indicate the CN being PS/MME or PS/SGSN, if there is a PS serviceavailable. The availability of the PS service may be based on the MME1308-MSC/VLR or SGSN 1310-MSC/VLR interactions over the interface thatconnects the nodes together. In examples, the MME 1308 may page the WTRU1302 in LTE for CS services. In examples, the SGSN 1310 may page theWTRU 1302 in UTRAN for CS services.

The corresponding CN controlling node 1308, 1310 may determine thateither a single PDP context may be used, or in examples, that each PDPcontexts will have similar parameter value such as the same IP addressfor a given WTRU 1302.

In addition, probing actions between involved network controlling nodes1308, 1310 may be defined for the core network association methods.

A first node, for example SGSN 1310, may send an MRA association requestmessage to the CN switching node, for example MME 1308, on the otherRAT. In examples, if the first node receives an attach request from theWTRU 1302, which may be in examples a successfully authenticated WTRU1302. The CN switching node may be determined based on the WTRU 1302location area-ID in the attach request. The first node may then be in apending state, e.g., MRA association pending state.

A second node, for example MME 1308, may receive an attach request or aregistration message such as tracking, routing, or location area update,from the same WTRU 1302, which may be a successfully authenticated WTRU1302. In examples, the second node may have already received the MRAassociation request from the first node, for example in case ofconcurrent attach method. In examples, the second node may then send anMRA association response message back to the first node. In examples,the second node may, for example for sequential attach methods, send anMRA association request message to the other node.

Both the first and second nodes may enter a ready state, for example anMRA association ready state. In examples, both nodes enter the readystate when both nodes have received an MRA association response.

The MRA association response may include at least one of a transactionidentifier, a timestamp, and/or an indication of accept/reject.

The MRA pending state may be bounded in time, upon which expiration thestate of the controlling node may be reverted and the association may bedeemed unsuccessful.

In examples, core network association may be triggered as a result of anattach or tracking, routing, location or area update method. The WTRU1302 may indicate which network to associate with, WTRU 1302 capability,and USIM subscription. The CN may ensure that same PDP context isconfigured. In examples, if association is not ready or established,then combined attach or separate attach may be rejected.

A RAN controlling node, for example eNodeB for EUTRA or NodeB or RNC forUTRA may initiate a request to the WTRU 1302 to terminate MRA operationover the connected RAT. The RAN controlling node may initiate therequest to terminate in response to a handover failure for another RATfor a given WTRU 1302. In examples, a RAN controlling node for exampleeNodeB for EUTRA or NodeB or RNC for UTRA may initiate a request to thecore network to terminate MRA operation and to remove the MRAassociation in response to a handover failure for one or more RATs for agiven WTRU 1302. Termination of MRA operation may include initiation ofa detach procedure for the concerned RATs.

In one method, the WTRU 1302 may implicitly detach, if it has not hadcommunication with the MME 1308 for a predetermined period of time. Inexamples, the WTRU 1302 may change the state of each of the concernedRATs to deregistered, detached, or an equivalent state. In examples, theWTRU 1302 may remove any dedicated configuration for the radio resourcesof each concerned RAT when it deregisters or detaches.

FIG. 14 is a schematic illustration of a flow diagram of an exampleWTRU-initiated combined detach method 1400 from an eUTRA (LTE/EPS) RAT.In 1450 of FIG. 14, the WTRU 1402 may initiate a detach method to detachitself from the core network by transmitting a combined detach request,for example, on the connection of the LTE RAT. In 1452 of FIG. 14, theWTRU 1402 may send a NAS message such as a detach request to the MME1406, the detach request 1452 may include one or more parameters such asGUTI and switch off. In examples, the detach request 1452 may include adetach type indication such as combined EPS/GPRS detach or combinedEPS/GPRS/IMSI detach. The type indication may depend on the WTRU's 1402condition and type of attach to the network. See FIG. 26 for additionalexamples of IEs.

The MME 1408 may deactivate the active EPS bearers in the SGW 1408 forthe WTRU 1402. In examples, the MME 1408 may deactivate the active EPSby, for example, the MME 1408 sending a delete session request (LBI) perPDN connection to the SGW 1408 and PGW 1412, and the PGW 1412 respondingby sending a delete session response as shown in 1452, 1454, 1456 and1458 of FIG. 14.

In 1460 of FIG. 14, the MME 1406 may send a detach notification, forexample a cause message to the associated SGSN 1404. In examples, thedetach notification may be sent to the SGSN 1404 when the WTRU 1402 isalso GPRS attached and for which the detach request included a detachtype that is either combined EPS/GPRS detach or combined EPS/GPRS/IMSIdetach. In examples, the cause may indicate a complete detach from thenetwork.

In 1462 of FIG. 14, the SGSN 1404 may deactivate the active PDP contextsin the SGW 1408 for the concerned WTRU 1402. In examples, this isachieved by, for example, the SGSN 1404 sending a delete session request(LBI) per PDN connection to the SGW 1408 and PGW 1412, and receiving adelete session response in 1468 of FIG. 14.

In 1470 of FIG. 14, the SGSN 1404 may send a detach acknowledge messageto the MME 1408. In 1472, the MME 1406 may send an IMSI DetachIndication (IMSI) message 1472 to the MSC/VLR 1410, if, for example, theconcerned WTRU 1402 was IMSI attached and the detach type indicatescombined EPS/IMSI or combined EPS/GPRS/IMSI.

In 1474 of FIG. 14, the MME 1406 may send a GPRS detach indicationmessage to the MSC/VLR 1410 to disassociate the MSC 1410 with the SGSN1404, if, for example, the WTRU 1402 was GPRS attached and the detachtype indicates combined EPS/GPRS or combined EPS/GPRS/IMSI.

In 1476 of FIG. 14, the MME 1406 may send an EPS detach indicationmessage 1476 to the MSC/VLR 1410 to disassociate the MSC 1410 with theMME 1406, if, for example, the WTRU 1402 was EPS attached and the detachtype indicates combined EPS/GPRS″ or EPS only or EPS/GPRS/IMSI.

In 1480 of FIG. 14, the WTRU 1402 may receive a detach accept messagefrom the MME 1406. In examples, the WTRU 1402 may change the state ofeach of the concerned RAT to a deregistered, detached, or equivalentstate. The order of 1472, 1474, and 1476 of FIG. 14 may vary.

FIG. 15 is schematic illustration of a flow diagram of an example WTRUinitiated combined detach method a UTRA (GPRS/UMTS/HSPA) RAT.

The WTRU 1502 may initiate a detach method to detach itself from thecore network by transmitting a combined detach request 1550, forexample, on the connection of the UTRAN RAT.

In 1550 of FIG. 15, the WTRU 1502 may send a NAS message such as adetach request 1550 to the SGSN 1504. The detach request 1550 mayinclude one or more parameters such as detach type, P-TMSI, P-TMSISignature, or Switch Off. In examples, the detach request 1550 mayinclude a detach type indication such as combined EPS/GPRS detach,combined EPS/IMSI detach, or combined EPS/GPRS/IMSI detach. The typeindication may depend on the WTRU's 1502 condition and type of attach tothe network. A more detailed example of such IE is disclosed below.

In 1552 of FIG. 15, the SGSN 1504 may deactivate the active PDP contextsin the GGSNs regarding the WTRU 1502, in the case of GPRS detach. Thismay be achieved by the SGSN 1504 sending a delete session request 1552to the SGW 1508 and PGW 1512, and the PGW 1512 sending a delete sessionresponse as shown in 1552, 1554, 1556 and 1558 of FIG. 15.

In 1560 of FIG. 15, the SGSN 1504 may send a detach notification causemessage to the associated MME 1506 for a WTRU 1502 that is also EPSattached, if, for example, the detach type is either EPS/GPRS detach,EPS/GPRS/IMSI, or EPS/IMSI detach. In examples, the cause may indicatecomplete detach for the WTRU 1502.

In 1562 of FIG. 15, the MME may deactivate the active PDP contexts inthe MME 1506 for the concerned WTRU 1502. In examples, this may beachieved by the MME 1506 sending a delete session request (LBI) 1562 perPDN connection to the SGW 1508 and PGW 1512, and receiving a deletesession response in 1568 of FIG. 15.

In 1570 of FIG. 15, the MME 1506 may send a detach acknowledge messageto the SGSN 1504.

In 1572 of FIG. 15, the SGSN 1504 or MME 1506 may send an IMSI detachindication (IMSI) message 1572 to the MSC/VLR 1510, if, for example,WTRU 1502 was IMSI attached. In examples, the SGSN 1504 sends IMSIdetach indication message 1572 if the detach type indicates combinedEPS/IMSI, combined EPS/GPRS/IMSI, or EPS/IMSI.

In 1574 of FIG. 15, the SGSN 1504 or MME 1506 may send a GPRS detachindication message 1574 to the MSC/VLR 1510 to disassociate MSC 1510with the SGSN 1504, if, for example, the WTRU 1502 was GPRS attached. Inexamples, the SGSN 1504 may send a GPRS detach indication message 1574if the detach type indicates combined EPS/GPRS or combinedEPS/GPRS/IMSI.

In 1576 of FIG. 15, the SGSN 1504 or MME 1506 may send an EPS detachindication (IMSI) message 1576 to the MSC/VLR 1510 to disassociate MSC1510 with MME 1506, if WTRU 1502 was EPS attached. The SGSN 1504 or MME1506 may send an EPS detach indication (IMSI) message 1576 to theMSC/VLR 1510, if the detach type indicates combined EPS/GPRS or EPS/GPRSor EPS/IMSI.

In 1580 of FIG. 15, the SGSN 1504 may send a detach accept message tothe WTRU 1502. If the switch off bit in the detach type IE indicatesthat detach is not due to a switch off situation, the SGSN 1504 may senda detach accept to the WTRU 1502. Note that the methods described inconjunction with FIG. 15 may also apply to the case when the WTRU 1502is performing a detach procedure for both a PS CN entity and also theMSC/VLR 1510.

Thus, a WTRU 1502 may initiate a combined detach method 1500 to the MME1506 that also indicates a detach request to the MSC/VLR 1510. The MME1506 may forward the detach indication to the MSC/VLR 1510. The WTRU1506 may also perform a combined detach method with an MSC/VLR 1510 andthe WTRU 1502 indicates detachment for both CS and PS-MME or PS-SGSN.The MSC/VLR 1510 then forwards the detach indication towards theappropriate CN node, for example MME 1506 or SGSN 1504.

In some examples, the MME 1506 may implicitly detach a WTRU 1502 if ithas not had communication with the WTRU 1502 for a predetermined periodof time. In examples, the MME 1506 initiates a procedure to remove theassociation for MRA operation in the core network for the concernedRATs. In another method, the WTRU 1502 may receive a combined detachrequest from the MME 1506, for example on the connection of the LTE RATto detach itself from the core network.

FIG. 16 is a schematic illustration of a flow diagram of an examplemobility management entity (MME 1606)-initiated combined detach method1600.

In 1650, the WTRU 1602 may receive a detach request message 1650 fromthe MME 1606. In examples, the WTRU 1602 may receive a detach requestmessage 1650 from the MME 1606 only if the WTRU 1602 is in ECM-CONNECTEDstate. The MME 1506 initiated detach method may be either explicit, forexample by O&M intervention, or implicit. In 1652-1672 may be similar asfor the WTRU 1602 initiated detach procedure described in conjunctionwith FIGS. 14 and 15. In 1676, the WTRU 1602 may send a detach acceptmessage 1676 to the MME 1606 any time after 1650. In examples, the WTRU1602 may send a detach accept message 1676 to the MME 1606 only if theWTRU 1602 receives the detach request message 1650 from the MME 1606 in1650. The eNodeB (not illustrated) may forward this NAS message to theMME 1606. The WTRU 1602 may change the state of each of the RATsassociated with MRA to a deregistered, detached or equivalent state.

In examples, the WTRU 1602 may remain attached to UTRAN (or MSC/VLR ifit was registered with it) when the MME 1606 sends the detach request1650 to the WTRU 1602. The MME 1606 may also indicate to the SGSN 1604and/or MSC/VLR 1610 that it is detaching the WTRU 1602 by, for example,sending the detach notification message 1660 to the SGSN and/or MSC/VLR.After the detach method 1600 is completed, the WTRU 1602 may power upthe RAT for which it is still attached (if this is not already poweredup) and continue its operation on that RAT.

In some examples, the SGSN 1604 may implicitly detach a WTRU 1602 if ithas not had communication with the WTRU for a predetermined period oftime. In examples, the SGSN 1604 initiates a method to remove theassociation for MRA operation in the core network for the MRA associatedRATs. In some examples, the WTRU 1602 may receive a combined detachrequest from the SGSN 1604, for example on the connection of the UTRANRAT to detach itself from the core network.

FIG. 17 is a schematic illustration of a flow diagram of an exampleserving general packet radio service (GPRS) support node(SGSN)-initiated combined detach method 1700. In 1750, the WTRU 1702 mayreceive a detach request message 1702 from the SGSN 1704. The detachrequest message 1702 may include a detach type. The SGSN 1704 may onlysend the detach request message 1750 if the WTRU 1702 is in a connectedstate. The SGSN 1704 initiated detach method 1700 may be eitherexplicit, for example by O&M intervention, or implicit. In FIG. 17, 1752through 1778 may be similar as for the WTRU 1702 initiated detachprocedure described in conjunction with FIGS. 14 and 15. In 1780, theWTRU 1702 may send a detach accept message 1780 to the SGSN 1704 anytime after 1750. In examples, the WTRU 1702 may send a detach acceptmessage 1780 to the SGSN 1704 only if the WTRU 1702 receives the detachRequest message 1750 from the SGSN 1704 in the step 1750. In examples,the WTRU 1702 may change the state of one or more of RATs associatedwith MRA to a deregistered, detached, or equivalent state.

The WTRU 1702 may remain attached in EUTRAN or MSC/VLR if it wasregistered with it when the SGSN 1704 sends the detach request 1750 tothe WTRU 1702. The SGSN 1704 may also indicate to the MME 1706 and/orMSC/VLR 1710 that it is detaching the WTRU 1702, by, for example,sending the detach notification message 1760 to one or both of the MME1706 and MSC/VLR 1710. After the detach method 1700 is completed, theWTRU 1702 may power up the RAT for which it is still attached, if thisis not already powered up, and continues its operation on that RAT.

In examples, the HLR (not illustrated) may detach a WTRU 1702 based onsome operator policies or subscription information. In examples, the HLRinitiates a procedure to remove the association for MRA operation in thecore network for one or more RATs associated with MRA. In examples, theWTRU 1702 may receive a combined detach request from the SGSN 1704 as aresult of an indication to do so from the HLR.

FIG. 18 is a flow diagram of an example home location register(HLR)-initiated combined detach method 1800. In 1850 of FIG. 18, the HLR1814 may send a cancel location, which may be an IMSI cancellation type,message 1850 to the SGSN 1804 with cancellation type set to subscriptionwithdrawn to request the immediate deletion of a subscriber's MM and PDPcontexts of the WTRU 1802 from the SGSN 1804.

In 1852 of FIG. 18, the WTRU 1802 may receive a detach request message1852 from the SGSN 1804. The SGSN 1804 informs the WTRU 1802 that it hasbeen detached by sending a detach request, which may have a detach type,to the WTRU 1802.

In FIG. 18, 1854 through 1882 may be similar as for the SGSN 1804initiated detach method. In 1884 of FIG. 18, the SGSN 1804 may confirmthe deletion of the MM and PDP contexts with a cancel location ack(IMSI) message 1884.

In examples, method 1800 may similarly be used when a WTRU 1802 isregistered with an MME 1806 or an MSC/VLR 1810. Thus, MME 1806 or anMSC/VLR 1810 may also receive the cancel location message from theHSS/HLR 1814. Similar actions may also be taken for the MME 1806 and anMSC/VLR 1810. For example, detaching the WTRU 1802 and sending a detachnotification to other CN nodes, for example a MME 1806 and/or SGSN 1804.

FIGS. 19, 20, and 21 disclose single attach methods for the dual RATaccess for a RAT in 3GPP network and a RAT in a non-3GPP network.Because the cross connection between a 3GPP network controlling node anda non-3GPP network controlling node is not always guaranteed, thefollowing approaches, i.e., going through the HSS/authentication,authorization and accounting (AAA) system to the non-3GPP site isdisclosed in FIGS. 19, 20, and 21, where the attach request starts froma 3GPP cell and 3GPP network, then communicates with a non-3GPP network.

FIG. 19 is schematic illustration of a flow diagram of an example of acombined attach request method 1900 from either a UTRA (GPRS/UMTS/HSPA)RAT or an EUTRA (EPS/LTE) RAT leading to an attachment of the WTRU toboth a 3GPP network and a non-3GPP network. In 1950 of FIG. 19, the WTRU1902 sends an attach request 1950 to the 3GPP network 1904 with attachtype of combined attach to 3GPP/non-3GPP network. In 1952 of FIG. 19,the 3GPP network 1904 triggers a WTRU 1902 authentication and securityprocedure. The WTRU 19902 may be registered to a server such as a 3GPPAAA Server 1954 and the AAA registers the WTRU in the non-3GPP network1956, as shown in 1950, 1952, 1954, and 1956 of FIG. 19. In FIG. 19,1958 may be a 3GPP attachment procedure.

FIG. 20 is schematic illustration of a flow diagram of an example of acombined attach request method 2000 from a non-3GPP RAT leading to anattachment of the WTRU to both 3GPP and non-3GPP network. In 2050 ofFIG. 20, the WTRU 2002 is registered in a non-3GPP system 2010 and thenon-3GPP system 2010 updates its gateway/trusted node with the WTRU's2002 subscriber information. The gateway/trusted node 2010 may updatethe AAA server 2008 with the WTRU's 2002 subscriber information. The AAAserver 2008 may then update the HLR 2006 with the WTRU's 2002 subscriberinformation. Then, the AAA server 2008 may trigger the WTRU's 2002registration to the HLR 2006. Based on the WTRU's 2002 subscriber dataand location, the HLR 2006 or AAA server 208 may send insert subscriberinformation to the MME/SGSN 2004, depending on the access technologyWTRU 2002 support and WTRU's 2002 subscriber information. The MME/SGSN2004 may then trigger 2062, which may perform an attachment method.

In examples, attach procedure 2062 of FIG. 20, may be performed. Inexamples, attach procedure 2062 of FIG. 20, may be as follows. The MME2004 updates the HSS that the WTRU 2002 is now under its service andgets the subscription information of the WTRU 2002 from the HSS. The MME2004 then creates a PDN connection for the WTRU 2002 towards the SGW/PDNGW, since IP address allocation is part of the attach procedure in LTE.

In examples, attach procedure 2062 of FIG. 20, may be as follows. Ifthere are active PDP contexts in the SGSN 2004 for the WTRU 2002, whichmay be present if the WTRU 2002 re-attaches to the same SGSN 2004without having properly detached from the SGSN 2004, then the SGSN 2004deletes these PDP contexts by sending delete PDP context request (TEID)messages to the appropriate GGSNs. The GGSNs acknowledge with delete PDPcontext response (TEID) messages. The SGSN 2004 may initiate locationupdate procedures toward the HLR 2006 and the old MSC/VLR to clean up anold location. The location update procedure may result in the deletionof any existing PDP context in the old SGSN and the appropriate GGSNs.The HLR 2006 may send subscription data from the HLR 2006 to the SGSN2004 through the exchange of insert subscriber data/insert subscriberdata ack messages between the HLR 2006 and the SGSN 2004. The SGSN 2004may then initiate a location update procedure toward the VLR and the HLR2006 to propagate the new location of the WTRU 2002 throughout thecommunications network.

After the 3GPP attachment is completed, the MME/SGSN 2004 may send aregistration complete to the AAA server 2006 as shown in 2064 of FIG.20. In 2066 of FIG. 20, the AAA server 2006 may update the non-3GPP nodewith the 3GPP attachment information, which may include one or more ofTAI, LAI, RAI, TMSI, and IP address.

In case the non-3GPP controlling node is reachable in the network by a3GPP controlling node, then the dual mode attach may be performed by onecontrolling node requesting the other on behalf of the WTRU 2002 toenable the WTRU 2002 across RAT access in the following sequence asdisclosed below in FIG. 21, which illustrates the 3GPP controlling noderequesting the non-3GPP controlling node.

FIG. 21 is a schematic illustration of a flow diagram of another exampleof a combined attach method 2100 leading to an attachment of the WTRU toboth a 3GPP network and a non-3GPP network. In 2150 of FIG. 21, the WTRU2102 after detecting both a 3GPP cell and a non-3GPP cell, initiates adual RAT network registration 2150 from a 3GPP RAT/Cell, for example anLTE cell, by sending a dual mode attach request 2150 with an attach typeEPS/non-3g.

In 2152 of FIG. 21, when the 3GPP-CN controlling node, for example MME2104, receives the dual mode attach request, it first authenticates theWTRU 2102 together with the HSS (not illustrated) in the 3GPP domain andmay generate security keys. In 2154 of FIG. 21, WTRU 2102 and CN 2104context is established with the gateway nodes, for example S-GW 2106 orP-GW 2108, or SGSN/GGSN (not illustrated). In 2120 of FIG. 21, based onthe non-3GPP RAT information found by the WTRU 2102 in the non-3GPPcell, the 3GPP-CN controlling node 2104 then may send a non-3GPP accessregistration to the non-3GPP local network control node, for example atrusted non-3GPP access node 2112, with necessary WTRU 2102 and thenon-3GPP cell information.

In 2158 of FIG. 21, the non-3GPP controlling node 2112 may exchangeauthentication and authorization information, which may includeinformation of the WTRU 2102 and information of the P-GW, with theHSS/AAA 2110 and gets the non-3GPP access authorization parameters backfor the WTRU 2102.

In 2160 of FIG. 21, the non-3GPP controlling node 2112 may then send anacknowledgement message back to the 3GPP controlling node 2104 notifyingthe success of the cross-RAT registration. In 2162 of FIG. 21, the 3GPPcontrolling node 2104 may then send the attach accept message back tothe WTRU 2102 with the operating parameters for the 3GPP network and thenon-3GPP network.

FIG. 22 schematically illustrates different methods for performingsession management. Illustrated in FIG. 22A is a RAT-specific sessionmanagement method where a message 2234A is sent from WTRU 2202 to a NASlevel entity 2212, which may be a SGSN of a UMTS system 2204, 2206. Themessage 2234 may be sent over the air interface 516. Illustrated in FIG.22B is proxy-based session management where message 2234 is sent fromthe WTRU 2202 to a NAS entity 2213, which may be an MME of a LTE system2214, 2207. The message 2234 may then be sent from the NAS entity 2213to the NAS 2212, which may be an SGSN of a UMTS system. The message 2234may include session management information for NAS 2212.

The WTRU 2202 may perform at least one of the following for mobilitymanagement. The WTRU 2202 may monitor the network for MRA support. TheWTRU 2202 may receive indications about support of MRA in registrationmessages, such as one or more of attach accept, attach reject, TAUaccept, TAU reject. The WTRU 2202 may receive an explicit indication ofnetwork support for MRA in other NAS messages or via OMA DM or OTA.

The WTRU 2202 may indicate its MRA capability in the registrationprocedure to a network. The WTRU 2202 may provide an indication of itssupport for MRA operation upon registration to the network. For example,the WTRU 2202 may indicate its support for MRA in one or more of thefollowing registration messages: attach Request, GMM attach request,location area update (LAU) request, routing area update (RAU) request,and tracking area update (TAU) request. In examples, this indication maybe included as part of the radio access capability IE or networkcapability IE, or any other new IE that may be defined for this purpose.

In examples, the WTRU 2202 may provide this indication via other NASmessages. For example, the indication for MRA support may be provided inthe EMM Information. The WTRU 2202 may indicate MRA support upon achange of WTRU 2202 setting such as that MRA operation is now supportedor activated in the WTRU 2202, or is now deactivated or not supported inthe WTRU 2202. For example, indications of support of MRA sent by theWTRU 2202 may be upon a change of support for MRA. For example, a WTRU2202 may indicate to the network whenever its MRA operation supportchanges from not supported or deactivated to supported or activated, orchanges from supported or activated to not supported or deactivated.

The WTRU may register to the core network (CN) domain for a plurality ofconcerned RATs that may be MRA-capable RATs. For example, RATs that mayhave been determined by the WTRU as MRA-capable. For example, if theWTRU is using LTE and UMTS for MRA operation, then the WTRU may registerto both MME and SGSN. In examples, the WTRU may also register to othernodes such as the MSC/VLR. The WTRU may perform such a registration tomore than one CN node upon the activation or indication of MRA support.Alternatively, such a registration may be done even if the WTRU remainsin idle mode in both RATs, or in at least one of the concerned RATs. Forexample, the WTRU, upon power on, may register to the necessary CNentities (such as MME, SGSN, and MSC/VLR) even if MRA operation will notbe used immediately after power on.

In examples, CN entities such as HSS, HLR, MME, SGSN, or MSC/VLR, mayhave one indication for every WTRU (e.g., in the subscription profile ofthe WTRU) to indicate whether or not MRA operation can be provided forthe WTRU. For example, upon attaching, the HSS may forward an indicationof whether or not MRA operation may be supported for a WTRU in theLocation Update ACK message that is sent by the HSS to the MME. Othernetwork entities such as SGSN, HSS, MSC/VLR, and HLR, may send similarmessages indicating that the WTRU may or may not be supported for MRAoperation. In examples, a WTRU may be permitted MRA operation for onlycertain services such as PS or CS only; PS in LTE, and PS in UMTS only;PS in LTE and PS in non-3GPP only; or, PS in LTE and PS in UTRAN and CSin UTRAN only.

In examples, the following may be subscription information for the WTRU:MRA operation is only allowed for one IP address, and MRA operation isonly allowed for traffic that is obtained via a connection to a specificAPN.

The mobility management methods disclosed above may be used fordifferent types of RATs and different CN entities. For example, a methoddisclosed for a WTRU in an LTE system with the WTRU and an MME entitycommunicating, may also be used by a WTRU in an UTRAN system with theWTRU and an SGSN entity communicating.

Registration methods are disclosed for a WTRU to perform registration onone or more of networks, RATs, or CN entities. The WTRU may register ondifferent CN entities that belong to different RATs in order to use MRAservices. A new registration type may be defined by the WTRU thatindicates to the network that MRA is required.

In examples, the WTRU may perform an attach procedure over LTE oranother network type by sending an attach request message with a newattach type IE, such as EPS attach with MRA. Alternatively, the WTRU mayuse an existing attach type such as EPS attach and include additional IEin the message such as WTRU's support for MRA. In examples, the WTRU maysend a new attach type such as “EPS/SGSN attach” or “EPS/SGSN/IMSIattach” to indicate dual registration to the MME/SGSN or the tripleregistration to the MME/SGSN/MSC, respectively. Other network entitiesand other network types may be used.

In examples, the CN entity that receives the message from the WTRU, forexample an MME entity, may register the WTRU in one or more other CNentities for performing MRA. The CN entity may register the WTRU in oneor more other CN entities in response to the WTRU's subscriptionindicating the WTRU is allowed MRA operation. In examples, the WTRU maybe registered to CN entities by the WTRU directly or by a CN entity inresponse to the WTRU registering with one or more CN entities.

In examples, the MME sends an attach accept message that indicates thatthe WTRU's registration to an LTE network has been successful. A NASmessage, or other type of message, may be sent to the WTRU indicatingthe WTRU should perform registration to certain other systems overanother RAT, such as UMTS, GERAN, or with certain entities such as SGSNor MSC/VLR, or with non-3GPP accesses. The message indicating that theWTRU should register with another network entity or another network overanother RAT may be sent based on network operator policy, subscriptioninformation (either locally at the MME or fetched by the MME from theHSS), location or load/congestion information.

In examples, the MME, or other network entity, performs a registrationto the required CN such as a SGSN or MSC/VLR on behalf of the WTRU. TheMME may then perform a registration procedure towards the SGSN using theS3 interface, or another interface that may connect these two networkentities. The MME or other network entity may use a new message type oran existing message type. The MME or other network entity indicates tothe recipient entity that the type of registration of the WTRU is an MRAregistration so that the WTRU is expected to simultaneously operate overat least two RATs.

In examples, one of the network entities may be a master entity that isresponsible for the WTRU's main registration or contexts. Networkentities such as the MME and the SGSN or the MSC/VLR may coordinate andagree as to which entities will be responsible for the WTRU's mainregistration or contexts. In examples, the master entity may be theinitiating node, or the CN entities may determine a master entity basedon operator policies or other conditions that may be defined locally inthese entities. In examples, the master node may be determined based onnetwork condition, for example, when resources of a particular networkare low, the master entity may be assigned to a different network.

In examples, the network entity, such as the MME, provides the other CNentities with the context information for the WTRU MRA operation. Forexample, the MME may provide the EPS bearer contexts to the SGSN andindicate the number of PDN connections, type of PDN connections, forexample, IPv4 or IPv6, and the number of default bearers. In examples,the MME may send information regarding one or both of the PDN GW and theSGW. For example, the MME may include the addresses of the PDN GW andSGW, tunnel endpoint ID for new bearers to be setup, and any otherinformation that may be relevant for the MRA operation of the WTRU. Inexamples, the MME may also inform other CN entities about the MRA of theWTRU. For example, the MME may send in a message to one or both of thePDN GW and SGW that a WTRU may operate in MRA mode. The SGSN, the PDNGW, or the SGW, or other network entities, may use the indication that aWTRU may operate in MRA mode to perform other actions for the WTRU. Forexample, a PDN GW may store for the WTRU context information for both aMME/SGW and a SGSN, so that the PDN GW. As another example, during theWTRU registration procedure, the MME may when it creates a new defaultbearer, instruct the SGW/PGW to prepare additional default bearersresources and bearer contexts for the WTRU through different RAT typessuch as SGSN or RNC, depending on the WTRU MRA capabilities. Inexamples, the SGW/PGW may use a single default bearer and establishmultiple dedicated bearers and multiple secondary PDP contexts.

In examples, a CN entity, for example SGSN, receiving instructions toprepare for WTRU MRA operation from a CN entity in a core network, mayaccept or reject the registration based on one or more of the networkoperator policy such as subscription information, which may be retrievedeither locally or remotely, location information, load, or congestioninformation.

If the other network entity, for example SGSN, receiving instructions toprepare for WTRU MRA operation, accepts the registration, the othernetwork entity, for example SGSN, send a message to the sending networkentity, for example, MME. In examples, the message sent to the sendingnetwork entity may be a new message type or an existing message typewith a new cause or an IE. The other network entity, SGSN in thisexample, may also include information to the sending network entity, theMME in this example, regarding an address for tunnel endpoints forcontrol or user plane. The other entity, in this example SGSN, may inthe response message to the sending entity, in this example MME, provideinformation regarding the WTRU. The information regarding the WTRU mayinclude one or more of S-TMSI, routing area identity, or location areaidentify, which may be obtained from a MSC/VLR.

In examples, if the other entity, in this example SGSN, rejects theregistration based on operator or subscription policies, then the otherentity may send a message to the sending entity indicating the rejectionof the registration, which may include an appropriate cause. Inexamples, the sending entity, which in this example is MME, or the WTRUmay re-attempt the registration based on some, e.g., timer that guardsregistration re-attempts.

The WTRU may receive an attach accept message that indicates that thecombined procedure has been accepted by both the sending network entity,in this example the MME, and the receiving entity, in this example theSGSN. In examples, the message may use a new value for the attach resultor update result) IE, the attach accept message may add new IE to theexisting attach accept message. In examples, the WTRU is provided with acommon NAS mobility management identity for both CNs and an identity fortwo PS domains and one for the CS domain. In examples, the WTRU isprovided with independent identifiers per CN or RAT. For example, theWTRU may be provided with an S-TMSI per LTE operation, an P-TMSI perGPRS operation, and a TMSI as per CS domain operation.

In examples, the WTRU is provided with a common periodic update timerand upon its expiry the WTRU performs a periodic update registration tothe necessary CN domains. The periodic update may be a combined periodicupdate which triggers combined registration or updates from a primary CNentity, which may be the CN entity that received the combined periodicupdate or register message, to the another CN entity that the WTRU isregistered with such as SGSN and/or MS C/VLR.

In examples, the WTRU may perform independent updates to the individualCN entities using existing methods. In examples, a periodic update orregistration message to one CN entity includes an indication of theregistration status of the WTRU with other CN entities along with one ormore of identification information of the CN entities such as RAI,P-TMSI, GUTTI, S-TMSI, and TMSI.

In examples, the WTRU may first register with one CN or RAT and when anevent that triggers MRA operation occurs, the WTRU may then register onanother RAT or CN. In examples, the WTRU may usetracking/routing/location area update messages as registration messages.

In examples, an MRA WTRU might be in idle mode on a given RAT while inconnected mode on another RAT. The transition between idle mode andconnected mode in each RAT may happen independently of each other. Inexamples, the WTRU may not be permitted to be in idle mode on one RATwhile in connected mode on another RAT. In examples, when a WTRU goesinto idle mode on a RAT, a timer with a predetermined time may bestarted to prevent the WTRU from staying in idle mode for more than apredetermined period of time without communicating over the RAT. Thetimer may be started in the WTRU, the core network, or the RAN.

In examples, the WTRU, the RAN, or the core network may transition fromMRA mode of operation to single RAT mode of operation. In examples, theWTRU, the RAN or the core network may request that the WTRU transitionfrom MRA mode to single RAT access mode.

In examples, a WTRU may be registered on several domains or with severalCN entities, for example MME and MSC/VLR, and may only power up the RATswhen there are parallel or simultaneous sessions running on each RAT orwhen sessions are controlled by different CN entities. For example, aWTRU that is registered to both an MME and an MSC/VLR and is operatingin MRA, and may use only MRA if there are both PS and CS services neededat the same time. For example, a WTRU in a LTE CN may perform CSFB whenthere is a CS call, but not use the PS for LTE. As another example, aWTRU with a PS session in LTE and a CS session in GERAN/UTRAN mayoperate in MRA, and thus may be using both a RAT to LTE and a RAT toGERAN/UTRAN.

In examples, triggers apply to either a WTRU or a network entity, orboth. In examples, the triggers may initiate an MRA operation, or mayterminate an MRA operation. In examples, the trigger may initiate amethod for the WTRU to enter MRA operation which may include the WTRUregistering on the core networks.

In examples, if the WTRU's subscription is such that there's a maximumbit rate that may be provided over one RAT, and there is an additionalservice request, for example, session management requests that requireany QoS class or additional resources, then a trigger may activate forthe WTRU to enter MRA operation. In examples, the type of servicerequested that triggers the trigger may determine the RAT for MRAoperation. For example, if a PS service is requested, then a RAT thatprovides PS service such as LTE may be activated for MRA operation. Asanother example, if the WTRU has an LTE RAT active, then a request forMO or MT CS services, for example SMS, SS, voice calls, may trigger theactivation/initiation of MRA over a RAT that provides CS.

A user may request MRA operation. For example, a user may request MRAoperation over a user interface, or the user may change a setting of theWTRU that triggers MRA operation. In examples, the settings of the WTRUmay be changed via OMA DM or OTA, which may trigger MRA operation.

In examples, the WTRU may receive an explicit indication to operate inMRA from any network entity in the system, for example, any RAN entitysuch as RNC, eNodeB, NodeB, or a CN entity, for example, MME or SGSN.

In examples, a trigger to enter MRA operation may be triggered uponreceipt by the WTRU of an indication that system supports MRA. Inexamples, if the WTRU receives an indication that the network supportsMRA operation, the WTRU may determine whether or not the user of theWTRU wants to enter MRA. In examples, the WTRU indicates to the userwhen the network does not support MRA.

In examples, a trigger to enter MRA operation may be triggered as aresult of the WTRL requesting a PDN connection to a particular APN orfor a particular service (MO or MT). In examples, a trigger to enter MRAoperation may be triggered after a request for an PDN connectivity, whena predetermined number of PDN connections have already been setup on oneRAT.

In examples, when the WTRU is VPLMN roaming, the VPLMN may activate MRAupon indication from HPLMN that this is allowed for the VPLMN inquestion.

In examples, lack of support of a service may trigger a trigger toactivate MRA. For example, lack of CSFB support may activate MRA for aWTRU so that it can still have both PS and CS services via LTE andUTRAN/GERAN respectively. As another example, lack of IMS or VoIPsupport in LTE (indicated in NAS or RRC messages) may trigger a triggerto activate MRA so that the WTRU can still get voice services via the CSdomain of GERAN/UTRAN.

In examples, a request to place a CS emergency call while a WTRU is inLTE may trigger a trigger for MRA operation to be activated to servicethe emergency call.

FIG. 23 schematically illustrates a table that illustrates an EPS attachtype information elements (IE) for Combined ATTACH Procedure with theintroduction of two new Information Element (IE). In examples, an EPSattach type information element (IE) for a combined detach procedure maybe defined to include combined EPS/GPRS/IMSI attach 2310, and combinedEPS/GPRS attach 2320. The new combined attach information elements 2310,2320 could be represented as bits 011 and 100, respectively.

FIG. 24 schematically illustrate a table that illustrates a modified EPSattach accept message for a combined attach procedure. The EPS attachaccept message 2410 encapsulates the new IE “UTRAN Attach Status”. Inexamples, the attach accept message 2410 is a combined attach methodwhere a single PDP context activation is used.

FIG. 25 schematically illustrates a table that illustrates a GPRS/UMTSAttach Status Information Element (IE) as discussed in conjunction withthe modified EPS attach accept message illustrated in FIG. 24. Thecontent of this GPRS/UMTS Attach Status Information Element (IE) is maybe the same as the usual GPRS/UMTS attach accept message contentdefined. In examples, the IE may also be a transparent container to theEPC network nodes such as MME with a final destination to the WTRU. TheGPRS/UMTS core network node such as SGSN may include additionalinformation beside the GPRS/UTRAN attach accept message. The IE mightalso include additional information to be processed and use by the EPCnodes such as MME. In examples, an attach accept message from onesystem, for example EPS, GPRS/UMTS, or non-3GPPS system, may beencapsulated in the attach accept message sent to the WTRU by the othersystem, for example EPS, GPRS/UTRAN, or non-3GPP network, and can beencapsulated as a transparent container to the system sending the finalattach accept message to the WTRU. Transparent container may meant thatthe network entities may not have to interpret or understand the contentof the message but may pass the message through the network.

FIG. 26 schematically illustrates a table that illustrates anotherexample of a modified EPS attach accept message content. Illustrated inFIG. 26 is UTRAN Attach Status 2610 and UTRAN activation of a PDPContext 2620 IE. Both 2610 and 2620 are information elements (IEs) andboth may be encapsulated in transparent containers addressed to theWTRU. UTRAN Attach Status 2610 may be for GPRS/UMTS.

FIG. 27 schematically illustrates a GPRS/UMTS PDP context messagecontent as an example of the modified EPS attach accept messageillustrated in FIG. 26.

FIG. 28 schematically illustrates GPRS/UMTS attach accept messagecontent that is same as the one depicted in FIG. 25. In examples,message content for UTRAN attach accept message content may be definedin accordance with the methods and apparatuses disclosed herein.

FIG. 29 schematically illustrates a modified table of informationelements (IE) for a detach type IE used in an EPS detach request messagefor a combined detach procedure. The following additional IEs aredefined: “Combined EPS/GPRS detach” 2910, “Combined EPS/GPRS/IMSIdetach” 2920, “Combined EPS/GPRS detach” 2930, and “CombinedEPS/GPRS/IMSI detach” 2940. In examples, the additional IEs may be usedfor examples disclosed herein.

FIG. 30 schematically illustrates a table of GPRS/UMTS attach type IEsused in a GPRS/UMTS attach request message for a combined attach. Inexamples, new GPRS attach type information elements can be defined for acombined detach procedure. The following additional IEs have beenintroduced: “Combined GPRS/EPS attach” 3010, “Combined GPRS/IMSI/EPSattach” 3020, and “Combined IMSI/EPS attach” 3030. In examples, the newGPRS attach types may be used for examples disclosed herein.

FIG. 31 schematically illustrates a modified table of GPRS/UMTS attachaccept message content for a combined attach procedure. In examples, newGPRS attach accept messages for combined attach could be defined. Forexample, EUTRAN Attach Accept 3110 and NONCE 3120 with a type referenceof bit string (128) and Presence of O may be defined. The new GPRSattach accept message for combined attach could be added to table attachaccept message. The new GPRS attach accept message may be used inexamples disclosed herein.

FIG. 32 schematically illustrates a table for EPS attach accept messagecontent as introduced in FIG. 31. In examples, a new EUTRAN attachaccept message content for a combined detach procedure could be definedin accordance with the apparatuses and methods disclosed herein.

FIG. 33 schematically illustrates another example of a table ofGPRS/UMTS attach accept message content for a combined attach procedure.In examples, an EUTRAN Attach Accept 3310 is an IE representing theresult of the GPRS/UMTS context activation result. NONCE may be 3320.The defined IEs may be used in examples disclosed herein.

FIG. 34 schematically illustrates a table for GPTS/UMTS activate PDPcontext accept message content as introduced in FIG. 33. The content issame as the content of the table in FIG. 27.

FIG. 35 schematically illustrates a table for EPS Attached Acceptmessage as introduced in FIG. 33. In examples, the content is same asthat of the table in FIG. 32.

FIG. 36 schematically illustrates a table for a GPRS/UMTS detach type ofinformation element for a combined detach. Six additional IEs have beenintroduced: “Combined GPRS/IMSI detach” 3610, “Combined EPS/IMSI detach”3620, “Combined EPS/GPRS/IMSI detach” 3630, “Combined EPS/GPRS detach”3640, “Combined EPS/IMSI detach” 3650, and “Combined EPS/GPRS/IMSIdetach” 3660. The new detach type information elements may be added totable detach message for combined detach procedure. The new detach typeinformation elements may be used with examples as disclosed herein.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

1. A wireless transmit/receive unit (WTRU) configured to perform amulti-radio access technology (RAT) access (MRA) operation, the WTRUcomprising: a WTRU non-access stratum (NAS) entity configured tocommunicate with a first NAS entity of a first core network and a secondNAS entity of a second core network; and a radio resource control (RRC)entity configured to control a first connection using a first RAT and asecond connection using a second RAT, wherein the first RAT is connectedto the first core network and the second RAT is connected to the secondcore network.
 2. A wireless transmit/receive unit (WTRU) configured toperform a multi-radio access technology (RAT) access (MRA) operation,the WTRU comprising: a WTRU non-access stratum (NAS) entity configuredto communicate with a first NAS entity of a first core network and asecond NAS entity of a second core network; a first radio resourcecontrol (RRC) entity configured to control a first connection using afirst RAT; and a second RRC entity configured to control a secondconnection using a second RAT, wherein the first RAT is connected to thefirst core network and the second RAT is connected to the second corenetwork.
 3. A wireless transmit/receive unit (WTRU) configured toperform a multi-radio access technology (RAT) access (MRA) operation,the WTRU comprising: a first WTRU non-access stratum (NAS) entityconfigured to communicate with a first NAS entity of a first corenetwork; a second WTRU NAS entity configured to communicate with asecond NAS entity of a second core network; and a radio resource control(RRC) entity configured to control a first connection using a first RATand a second connection using a second RAT, wherein the first RAT isconnected to the first core network and the second RAT is connected tothe second core network.
 4. A wireless transmit/receive unit (WTRU)configured to perform a multi-radio access technology (RAT) access (MRA)operation, the WTRU comprising: a first WTRU non-access stratum (NAS)entity configured to communicate with a first NAS entity of a first corenetwork; a second WTRU NAS entity configured to communicate with asecond NAS entity of a second core network; and a first radio resourcecontrol (RRC) entity configured to control a first connection using afirst RAT; and a second RRC entity configured to control a secondconnection using a second RAT, wherein the first RAT is connected to thefirst core network and the second RAT is connected to the second corenetwork.
 5. The WTRU of claim 1, wherein the first RAT and the secondRAT are different ones of: long term evolution (LTE), (LTE-A), universalmobile telecommunication system (UMTS), UMTS terrestrial radio accessfrequency division duplex (UTRA-FDD), wideband channel division multipleaccess (WCDMA), UMTS terrestrial radio access time division duplex(UTRA-TDD), UMTS terrestrial radio access time division duplex high chiprate (UTRA-TDD HCR), UMTS terrestrial radio access time division duplexlow chip rate (UTRA-TDD LCR), high speed packet access (HSPA),high-speed downlink packet access (HSDPA), high-speed uplink packetaccess (HSUPA), global system for mobile communications (GSM), enhanceddata rates for GSM evolution (EDGE), 802.11b, 802.11a, 802.11g, 802.11n,802.16a, 802.16e, 802.20, code division multiple access (CDMA) 20001 x,CDMA2000, and evolution-data optimized (EV-DO).
 6. The WTRU of claim 1,wherein the WTRU is configured to select a first cell for the first RATbased on information stored in the WTRU that indicates which cellssupport MRA operation.
 7. The WTRU of claim 1, wherein the WTRU isconfigured to select a first cell for the first RAT based on a signalreceived from the first core network, wherein the signal is one of abroadcast signal or a dedicated signal, and wherein the signal comprisesinformation regarding cells of the first core network that support MRAoperation.
 8. The WTRU of claim 1, wherein MRA operation is triggered byone or more of the following: the WTRU requesting a connection to anAPN, the WTRU requesting a predetermined QoS, the WTRU requesting aconnection to a particular IP address, the WTRU requesting voiceservice, the WTRU requesting data service, the WTRU requesting SMSservice, or by the WTRU specifying a new establishment cause as a resultof one of the following: an overload condition, an event matching anoperator policy trigger, or an indication stored in the subscriberprofile.
 9. The WTRU of claim 1, wherein the WTRU is further configuredto perform a first attach method to attach to the first core network andafter attaching to the first core network, then to perform a secondattach method to attach to the second core network.
 10. The WTRU ofclaim 1, wherein the WTRU is further configured to perform an attachmethod to attach to the first core network and the second core network,wherein the attach method sends a message to the first core network withparameters to attach to the second core network.
 11. The WTRU of claim1, wherein the NAS entity communicates with the first NAS entity and thesecond NAS entity using the first RAT to perform mobility management.12. The WTRU of claim 1, wherein the first RAT operates on one or morefrequencies, and the second RAT operates on one or more differentfrequencies.
 13. The WTRU of claim 3, wherein the first WTRU NAS entityis configured to communicate with the second WTRU NAS entity tocoordinate the delivery of packet switched (PS) data.
 14. The WTRU ofclaim 3, wherein the RRC entity is further configured to control a firstinstance of an RRC to manage the first RAT, and to control a secondinstance of an RRC to manage the second RAT.
 15. A method of a wirelesstransmit/receive unit (WTRU) performing a multi-radio access technology(RAT) access (MRA) operation, the method comprising: determining a firstcell of a first RAT that supports MRA operation; attaching to a firstNAS entity of a first core network via the first cell using a WTRUnon-access stratum (NAS) entity configured to communicate with the firstNAS entity of the first core network and a second NAS entity of a secondcore network, and using a radio resource control (RRC) entity configuredto control a first connection using the first RAT and a secondconnection using a second RAT, wherein the first RAT is connected to thefirst core network and the second RAT is connected to the second corenetwork; determining a second cell of the second RAT that supports MRAoperation; and attaching to the second NAS entity using the WRTU NASentity and the RRC entity.
 16. The method of claim 15, wherein theattaching to the second cell comprises: sending a message to the firstNAS entity of the first core network with parameters to attach to thesecond NAS entity of the second core network; and attaching to thesecond NAS entity using the WTRU NAS entity and the RRC entity.
 17. Themethod as in claim 15, wherein the attaching to the first NAS entity andthe attaching to the second NAS entity are performed simultaneously. 18.A method of a wireless transmit/receive unit (WTRU) performing amulti-radio access technology (RAT) access (MRA) operation, the methodcomprising: determining a first cell of a first RAT that supports MRAoperation; attaching to a first NAS entity of a first core network viathe first cell using a WTRU non-access stratum (NAS) entity configuredto communicate with the first NAS entity of the first core network and asecond NAS entity of a second core network, and using a first radioresource control (RRC) entity configured to control a first connectionusing the first RAT, wherein the first RAT is connected to the firstcore network; determining a second cell of a second RAT that supportsMRA operation; and attaching to the second NAS entity via the secondcell using the WRTU NAS entity and a second RRC entity configured tocontrol a second connection using the second RAT, wherein the second RATis connected to the second core network.
 19. The method of claim 18,wherein the NAS entity communicates with the first NAS entity and thesecond NAS entity using the first RAT to perform session management. 20.A method of a wireless transmit/receive unit (WTRU) performing amulti-radio access technology (RAT) access (MRA) operation, the methodcomprising: determining a first cell of a first RAT that supports MRAoperation; attaching to a first NAS entity of a first core network viathe first cell using a first WTRU non-access stratum (NAS) entityconfigured to communicate with a first NAS entity of a first corenetwork, and using a radio resource control (RRC) entity configured tocontrol a first connection using the first RAT and a second connectionusing a second RAT, wherein the first RAT is connected to the first corenetwork and the second RAT is connected to the second core network;determining a second cell of the second RAT that supports MRA operation;and attaching to the second NAS entity via the second cell using asecond WTRU NAS entity configured to communicate with the second NASentity of the second core network and the RRC entity.